From 4710c53dcad1ebf3755f3efb9e80ac24bd72a9b2 Mon Sep 17 00:00:00 2001
From: darylm503 <darylm503@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Mon, 16 Apr 2012 22:12:42 +0000
Subject: AppPkg/Applications/Python: Add Python 2.7.2 sources since the
 release of Python 2.7.3 made them unavailable from the python.org web site.

These files are a subset of the python-2.7.2.tgz distribution from python.org.  Changed files from PyMod-2.7.2 have been copied into the corresponding directories of this tree, replacing the original files in the distribution.

Signed-off-by: daryl.mcdaniel@intel.com


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13197 6f19259b-4bc3-4df7-8a09-765794883524
---
 .../Python/Python-2.7.2/Modules/itertoolsmodule.c  | 4097 ++++++++++++++++++++
 1 file changed, 4097 insertions(+)
 create mode 100644 AppPkg/Applications/Python/Python-2.7.2/Modules/itertoolsmodule.c

(limited to 'AppPkg/Applications/Python/Python-2.7.2/Modules/itertoolsmodule.c')

diff --git a/AppPkg/Applications/Python/Python-2.7.2/Modules/itertoolsmodule.c b/AppPkg/Applications/Python/Python-2.7.2/Modules/itertoolsmodule.c
new file mode 100644
index 0000000000..44f9017fd0
--- /dev/null
+++ b/AppPkg/Applications/Python/Python-2.7.2/Modules/itertoolsmodule.c
@@ -0,0 +1,4097 @@
+
+#include "Python.h"
+#include "structmember.h"
+
+/* Itertools module written and maintained
+   by Raymond D. Hettinger <python@rcn.com>
+   Copyright (c) 2003 Python Software Foundation.
+   All rights reserved.
+*/
+
+
+/* groupby object ***********************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *it;
+    PyObject *keyfunc;
+    PyObject *tgtkey;
+    PyObject *currkey;
+    PyObject *currvalue;
+} groupbyobject;
+
+static PyTypeObject groupby_type;
+static PyObject *_grouper_create(groupbyobject *, PyObject *);
+
+static PyObject *
+groupby_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    static char *kwargs[] = {"iterable", "key", NULL};
+    groupbyobject *gbo;
+    PyObject *it, *keyfunc = Py_None;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|O:groupby", kwargs,
+                                     &it, &keyfunc))
+        return NULL;
+
+    gbo = (groupbyobject *)type->tp_alloc(type, 0);
+    if (gbo == NULL)
+        return NULL;
+    gbo->tgtkey = NULL;
+    gbo->currkey = NULL;
+    gbo->currvalue = NULL;
+    gbo->keyfunc = keyfunc;
+    Py_INCREF(keyfunc);
+    gbo->it = PyObject_GetIter(it);
+    if (gbo->it == NULL) {
+        Py_DECREF(gbo);
+        return NULL;
+    }
+    return (PyObject *)gbo;
+}
+
+static void
+groupby_dealloc(groupbyobject *gbo)
+{
+    PyObject_GC_UnTrack(gbo);
+    Py_XDECREF(gbo->it);
+    Py_XDECREF(gbo->keyfunc);
+    Py_XDECREF(gbo->tgtkey);
+    Py_XDECREF(gbo->currkey);
+    Py_XDECREF(gbo->currvalue);
+    Py_TYPE(gbo)->tp_free(gbo);
+}
+
+static int
+groupby_traverse(groupbyobject *gbo, visitproc visit, void *arg)
+{
+    Py_VISIT(gbo->it);
+    Py_VISIT(gbo->keyfunc);
+    Py_VISIT(gbo->tgtkey);
+    Py_VISIT(gbo->currkey);
+    Py_VISIT(gbo->currvalue);
+    return 0;
+}
+
+static PyObject *
+groupby_next(groupbyobject *gbo)
+{
+    PyObject *newvalue, *newkey, *r, *grouper, *tmp;
+
+    /* skip to next iteration group */
+    for (;;) {
+        if (gbo->currkey == NULL)
+            /* pass */;
+        else if (gbo->tgtkey == NULL)
+            break;
+        else {
+            int rcmp;
+
+            rcmp = PyObject_RichCompareBool(gbo->tgtkey,
+                                            gbo->currkey, Py_EQ);
+            if (rcmp == -1)
+                return NULL;
+            else if (rcmp == 0)
+                break;
+        }
+
+        newvalue = PyIter_Next(gbo->it);
+        if (newvalue == NULL)
+            return NULL;
+
+        if (gbo->keyfunc == Py_None) {
+            newkey = newvalue;
+            Py_INCREF(newvalue);
+        } else {
+            newkey = PyObject_CallFunctionObjArgs(gbo->keyfunc,
+                                                  newvalue, NULL);
+            if (newkey == NULL) {
+                Py_DECREF(newvalue);
+                return NULL;
+            }
+        }
+
+        tmp = gbo->currkey;
+        gbo->currkey = newkey;
+        Py_XDECREF(tmp);
+
+        tmp = gbo->currvalue;
+        gbo->currvalue = newvalue;
+        Py_XDECREF(tmp);
+    }
+
+    Py_INCREF(gbo->currkey);
+    tmp = gbo->tgtkey;
+    gbo->tgtkey = gbo->currkey;
+    Py_XDECREF(tmp);
+
+    grouper = _grouper_create(gbo, gbo->tgtkey);
+    if (grouper == NULL)
+        return NULL;
+
+    r = PyTuple_Pack(2, gbo->currkey, grouper);
+    Py_DECREF(grouper);
+    return r;
+}
+
+PyDoc_STRVAR(groupby_doc,
+"groupby(iterable[, keyfunc]) -> create an iterator which returns\n\
+(key, sub-iterator) grouped by each value of key(value).\n");
+
+static PyTypeObject groupby_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.groupby",                /* tp_name */
+    sizeof(groupbyobject),              /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)groupby_dealloc,        /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    groupby_doc,                        /* tp_doc */
+    (traverseproc)groupby_traverse,     /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)groupby_next,         /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    groupby_new,                        /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* _grouper object (internal) ************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *parent;
+    PyObject *tgtkey;
+} _grouperobject;
+
+static PyTypeObject _grouper_type;
+
+static PyObject *
+_grouper_create(groupbyobject *parent, PyObject *tgtkey)
+{
+    _grouperobject *igo;
+
+    igo = PyObject_GC_New(_grouperobject, &_grouper_type);
+    if (igo == NULL)
+        return NULL;
+    igo->parent = (PyObject *)parent;
+    Py_INCREF(parent);
+    igo->tgtkey = tgtkey;
+    Py_INCREF(tgtkey);
+
+    PyObject_GC_Track(igo);
+    return (PyObject *)igo;
+}
+
+static void
+_grouper_dealloc(_grouperobject *igo)
+{
+    PyObject_GC_UnTrack(igo);
+    Py_DECREF(igo->parent);
+    Py_DECREF(igo->tgtkey);
+    PyObject_GC_Del(igo);
+}
+
+static int
+_grouper_traverse(_grouperobject *igo, visitproc visit, void *arg)
+{
+    Py_VISIT(igo->parent);
+    Py_VISIT(igo->tgtkey);
+    return 0;
+}
+
+static PyObject *
+_grouper_next(_grouperobject *igo)
+{
+    groupbyobject *gbo = (groupbyobject *)igo->parent;
+    PyObject *newvalue, *newkey, *r;
+    int rcmp;
+
+    if (gbo->currvalue == NULL) {
+        newvalue = PyIter_Next(gbo->it);
+        if (newvalue == NULL)
+            return NULL;
+
+        if (gbo->keyfunc == Py_None) {
+            newkey = newvalue;
+            Py_INCREF(newvalue);
+        } else {
+            newkey = PyObject_CallFunctionObjArgs(gbo->keyfunc,
+                                                  newvalue, NULL);
+            if (newkey == NULL) {
+                Py_DECREF(newvalue);
+                return NULL;
+            }
+        }
+
+        assert(gbo->currkey == NULL);
+        gbo->currkey = newkey;
+        gbo->currvalue = newvalue;
+    }
+
+    assert(gbo->currkey != NULL);
+    rcmp = PyObject_RichCompareBool(igo->tgtkey, gbo->currkey, Py_EQ);
+    if (rcmp <= 0)
+        /* got any error or current group is end */
+        return NULL;
+
+    r = gbo->currvalue;
+    gbo->currvalue = NULL;
+    Py_CLEAR(gbo->currkey);
+
+    return r;
+}
+
+static PyTypeObject _grouper_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools._grouper",               /* tp_name */
+    sizeof(_grouperobject),             /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)_grouper_dealloc,       /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,            /* tp_flags */
+    0,                                  /* tp_doc */
+    (traverseproc)_grouper_traverse,/* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)_grouper_next,        /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    0,                                  /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+
+/* tee object and with supporting function and objects ***************/
+
+/* The teedataobject pre-allocates space for LINKCELLS number of objects.
+   To help the object fit neatly inside cache lines (space for 16 to 32
+   pointers), the value should be a multiple of 16 minus  space for
+   the other structure members including PyHEAD overhead.  The larger the
+   value, the less memory overhead per object and the less time spent
+   allocating/deallocating new links.  The smaller the number, the less
+   wasted space and the more rapid freeing of older data.
+*/
+#define LINKCELLS 57
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *it;
+    int numread;
+    PyObject *nextlink;
+    PyObject *(values[LINKCELLS]);
+} teedataobject;
+
+typedef struct {
+    PyObject_HEAD
+    teedataobject *dataobj;
+    int index;
+    PyObject *weakreflist;
+} teeobject;
+
+static PyTypeObject teedataobject_type;
+
+static PyObject *
+teedataobject_new(PyObject *it)
+{
+    teedataobject *tdo;
+
+    tdo = PyObject_GC_New(teedataobject, &teedataobject_type);
+    if (tdo == NULL)
+        return NULL;
+
+    tdo->numread = 0;
+    tdo->nextlink = NULL;
+    Py_INCREF(it);
+    tdo->it = it;
+    PyObject_GC_Track(tdo);
+    return (PyObject *)tdo;
+}
+
+static PyObject *
+teedataobject_jumplink(teedataobject *tdo)
+{
+    if (tdo->nextlink == NULL)
+        tdo->nextlink = teedataobject_new(tdo->it);
+    Py_XINCREF(tdo->nextlink);
+    return tdo->nextlink;
+}
+
+static PyObject *
+teedataobject_getitem(teedataobject *tdo, int i)
+{
+    PyObject *value;
+
+    assert(i < LINKCELLS);
+    if (i < tdo->numread)
+        value = tdo->values[i];
+    else {
+        /* this is the lead iterator, so fetch more data */
+        assert(i == tdo->numread);
+        value = PyIter_Next(tdo->it);
+        if (value == NULL)
+            return NULL;
+        tdo->numread++;
+        tdo->values[i] = value;
+    }
+    Py_INCREF(value);
+    return value;
+}
+
+static int
+teedataobject_traverse(teedataobject *tdo, visitproc visit, void * arg)
+{
+    int i;
+    Py_VISIT(tdo->it);
+    for (i = 0; i < tdo->numread; i++)
+        Py_VISIT(tdo->values[i]);
+    Py_VISIT(tdo->nextlink);
+    return 0;
+}
+
+static int
+teedataobject_clear(teedataobject *tdo)
+{
+    int i;
+    Py_CLEAR(tdo->it);
+    for (i=0 ; i<tdo->numread ; i++)
+        Py_CLEAR(tdo->values[i]);
+    Py_CLEAR(tdo->nextlink);
+    return 0;
+}
+
+static void
+teedataobject_dealloc(teedataobject *tdo)
+{
+    PyObject_GC_UnTrack(tdo);
+    teedataobject_clear(tdo);
+    PyObject_GC_Del(tdo);
+}
+
+PyDoc_STRVAR(teedataobject_doc, "Data container common to multiple tee objects.");
+
+static PyTypeObject teedataobject_type = {
+    PyVarObject_HEAD_INIT(0, 0)         /* Must fill in type value later */
+    "itertools.tee_dataobject",                 /* tp_name */
+    sizeof(teedataobject),                      /* tp_basicsize */
+    0,                                          /* tp_itemsize */
+    /* methods */
+    (destructor)teedataobject_dealloc,          /* tp_dealloc */
+    0,                                          /* tp_print */
+    0,                                          /* tp_getattr */
+    0,                                          /* tp_setattr */
+    0,                                          /* tp_compare */
+    0,                                          /* tp_repr */
+    0,                                          /* tp_as_number */
+    0,                                          /* tp_as_sequence */
+    0,                                          /* tp_as_mapping */
+    0,                                          /* tp_hash */
+    0,                                          /* tp_call */
+    0,                                          /* tp_str */
+    PyObject_GenericGetAttr,                    /* tp_getattro */
+    0,                                          /* tp_setattro */
+    0,                                          /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,            /* tp_flags */
+    teedataobject_doc,                          /* tp_doc */
+    (traverseproc)teedataobject_traverse,       /* tp_traverse */
+    (inquiry)teedataobject_clear,               /* tp_clear */
+    0,                                          /* tp_richcompare */
+    0,                                          /* tp_weaklistoffset */
+    0,                                          /* tp_iter */
+    0,                                          /* tp_iternext */
+    0,                                          /* tp_methods */
+    0,                                          /* tp_members */
+    0,                                          /* tp_getset */
+    0,                                          /* tp_base */
+    0,                                          /* tp_dict */
+    0,                                          /* tp_descr_get */
+    0,                                          /* tp_descr_set */
+    0,                                          /* tp_dictoffset */
+    0,                                          /* tp_init */
+    0,                                          /* tp_alloc */
+    0,                                          /* tp_new */
+    PyObject_GC_Del,                            /* tp_free */
+};
+
+
+static PyTypeObject tee_type;
+
+static PyObject *
+tee_next(teeobject *to)
+{
+    PyObject *value, *link;
+
+    if (to->index >= LINKCELLS) {
+        link = teedataobject_jumplink(to->dataobj);
+        Py_DECREF(to->dataobj);
+        to->dataobj = (teedataobject *)link;
+        to->index = 0;
+    }
+    value = teedataobject_getitem(to->dataobj, to->index);
+    if (value == NULL)
+        return NULL;
+    to->index++;
+    return value;
+}
+
+static int
+tee_traverse(teeobject *to, visitproc visit, void *arg)
+{
+    Py_VISIT((PyObject *)to->dataobj);
+    return 0;
+}
+
+static PyObject *
+tee_copy(teeobject *to)
+{
+    teeobject *newto;
+
+    newto = PyObject_GC_New(teeobject, &tee_type);
+    if (newto == NULL)
+        return NULL;
+    Py_INCREF(to->dataobj);
+    newto->dataobj = to->dataobj;
+    newto->index = to->index;
+    newto->weakreflist = NULL;
+    PyObject_GC_Track(newto);
+    return (PyObject *)newto;
+}
+
+PyDoc_STRVAR(teecopy_doc, "Returns an independent iterator.");
+
+static PyObject *
+tee_fromiterable(PyObject *iterable)
+{
+    teeobject *to;
+    PyObject *it = NULL;
+
+    it = PyObject_GetIter(iterable);
+    if (it == NULL)
+        return NULL;
+    if (PyObject_TypeCheck(it, &tee_type)) {
+        to = (teeobject *)tee_copy((teeobject *)it);
+        goto done;
+    }
+
+    to = PyObject_GC_New(teeobject, &tee_type);
+    if (to == NULL)
+        goto done;
+    to->dataobj = (teedataobject *)teedataobject_new(it);
+    if (!to->dataobj) {
+        PyObject_GC_Del(to);
+        to = NULL;
+        goto done;
+    }
+
+    to->index = 0;
+    to->weakreflist = NULL;
+    PyObject_GC_Track(to);
+done:
+    Py_XDECREF(it);
+    return (PyObject *)to;
+}
+
+static PyObject *
+tee_new(PyTypeObject *type, PyObject *args, PyObject *kw)
+{
+    PyObject *iterable;
+
+    if (!PyArg_UnpackTuple(args, "tee", 1, 1, &iterable))
+        return NULL;
+    return tee_fromiterable(iterable);
+}
+
+static int
+tee_clear(teeobject *to)
+{
+    if (to->weakreflist != NULL)
+        PyObject_ClearWeakRefs((PyObject *) to);
+    Py_CLEAR(to->dataobj);
+    return 0;
+}
+
+static void
+tee_dealloc(teeobject *to)
+{
+    PyObject_GC_UnTrack(to);
+    tee_clear(to);
+    PyObject_GC_Del(to);
+}
+
+PyDoc_STRVAR(teeobject_doc,
+"Iterator wrapped to make it copyable");
+
+static PyMethodDef tee_methods[] = {
+    {"__copy__",        (PyCFunction)tee_copy,  METH_NOARGS, teecopy_doc},
+    {NULL,              NULL}           /* sentinel */
+};
+
+static PyTypeObject tee_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.tee",                    /* tp_name */
+    sizeof(teeobject),                  /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)tee_dealloc,            /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    0,                                  /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,            /* tp_flags */
+    teeobject_doc,                      /* tp_doc */
+    (traverseproc)tee_traverse,         /* tp_traverse */
+    (inquiry)tee_clear,                 /* tp_clear */
+    0,                                  /* tp_richcompare */
+    offsetof(teeobject, weakreflist),           /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)tee_next,             /* tp_iternext */
+    tee_methods,                        /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    tee_new,                            /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+static PyObject *
+tee(PyObject *self, PyObject *args)
+{
+    Py_ssize_t i, n=2;
+    PyObject *it, *iterable, *copyable, *result;
+
+    if (!PyArg_ParseTuple(args, "O|n", &iterable, &n))
+        return NULL;
+    if (n < 0) {
+        PyErr_SetString(PyExc_ValueError, "n must be >= 0");
+        return NULL;
+    }
+    result = PyTuple_New(n);
+    if (result == NULL)
+        return NULL;
+    if (n == 0)
+        return result;
+    it = PyObject_GetIter(iterable);
+    if (it == NULL) {
+        Py_DECREF(result);
+        return NULL;
+    }
+    if (!PyObject_HasAttrString(it, "__copy__")) {
+        copyable = tee_fromiterable(it);
+        Py_DECREF(it);
+        if (copyable == NULL) {
+            Py_DECREF(result);
+            return NULL;
+        }
+    } else
+        copyable = it;
+    PyTuple_SET_ITEM(result, 0, copyable);
+    for (i=1 ; i<n ; i++) {
+        copyable = PyObject_CallMethod(copyable, "__copy__", NULL);
+        if (copyable == NULL) {
+            Py_DECREF(result);
+            return NULL;
+        }
+        PyTuple_SET_ITEM(result, i, copyable);
+    }
+    return result;
+}
+
+PyDoc_STRVAR(tee_doc,
+"tee(iterable, n=2) --> tuple of n independent iterators.");
+
+
+/* cycle object **********************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *it;
+    PyObject *saved;
+    int firstpass;
+} cycleobject;
+
+static PyTypeObject cycle_type;
+
+static PyObject *
+cycle_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    PyObject *it;
+    PyObject *iterable;
+    PyObject *saved;
+    cycleobject *lz;
+
+    if (type == &cycle_type && !_PyArg_NoKeywords("cycle()", kwds))
+        return NULL;
+
+    if (!PyArg_UnpackTuple(args, "cycle", 1, 1, &iterable))
+        return NULL;
+
+    /* Get iterator. */
+    it = PyObject_GetIter(iterable);
+    if (it == NULL)
+        return NULL;
+
+    saved = PyList_New(0);
+    if (saved == NULL) {
+        Py_DECREF(it);
+        return NULL;
+    }
+
+    /* create cycleobject structure */
+    lz = (cycleobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_DECREF(it);
+        Py_DECREF(saved);
+        return NULL;
+    }
+    lz->it = it;
+    lz->saved = saved;
+    lz->firstpass = 0;
+
+    return (PyObject *)lz;
+}
+
+static void
+cycle_dealloc(cycleobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->saved);
+    Py_XDECREF(lz->it);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+cycle_traverse(cycleobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->it);
+    Py_VISIT(lz->saved);
+    return 0;
+}
+
+static PyObject *
+cycle_next(cycleobject *lz)
+{
+    PyObject *item;
+    PyObject *it;
+    PyObject *tmp;
+
+    while (1) {
+        item = PyIter_Next(lz->it);
+        if (item != NULL) {
+            if (!lz->firstpass && PyList_Append(lz->saved, item)) {
+                Py_DECREF(item);
+                return NULL;
+            }
+            return item;
+        }
+        if (PyErr_Occurred()) {
+            if (PyErr_ExceptionMatches(PyExc_StopIteration))
+                PyErr_Clear();
+            else
+                return NULL;
+        }
+        if (PyList_Size(lz->saved) == 0)
+            return NULL;
+        it = PyObject_GetIter(lz->saved);
+        if (it == NULL)
+            return NULL;
+        tmp = lz->it;
+        lz->it = it;
+        lz->firstpass = 1;
+        Py_DECREF(tmp);
+    }
+}
+
+PyDoc_STRVAR(cycle_doc,
+"cycle(iterable) --> cycle object\n\
+\n\
+Return elements from the iterable until it is exhausted.\n\
+Then repeat the sequence indefinitely.");
+
+static PyTypeObject cycle_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.cycle",                  /* tp_name */
+    sizeof(cycleobject),                /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)cycle_dealloc,          /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    cycle_doc,                          /* tp_doc */
+    (traverseproc)cycle_traverse,       /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)cycle_next,           /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    cycle_new,                          /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* dropwhile object **********************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *func;
+    PyObject *it;
+    long         start;
+} dropwhileobject;
+
+static PyTypeObject dropwhile_type;
+
+static PyObject *
+dropwhile_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    PyObject *func, *seq;
+    PyObject *it;
+    dropwhileobject *lz;
+
+    if (type == &dropwhile_type && !_PyArg_NoKeywords("dropwhile()", kwds))
+        return NULL;
+
+    if (!PyArg_UnpackTuple(args, "dropwhile", 2, 2, &func, &seq))
+        return NULL;
+
+    /* Get iterator. */
+    it = PyObject_GetIter(seq);
+    if (it == NULL)
+        return NULL;
+
+    /* create dropwhileobject structure */
+    lz = (dropwhileobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_DECREF(it);
+        return NULL;
+    }
+    Py_INCREF(func);
+    lz->func = func;
+    lz->it = it;
+    lz->start = 0;
+
+    return (PyObject *)lz;
+}
+
+static void
+dropwhile_dealloc(dropwhileobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->func);
+    Py_XDECREF(lz->it);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+dropwhile_traverse(dropwhileobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->it);
+    Py_VISIT(lz->func);
+    return 0;
+}
+
+static PyObject *
+dropwhile_next(dropwhileobject *lz)
+{
+    PyObject *item, *good;
+    PyObject *it = lz->it;
+    long ok;
+    PyObject *(*iternext)(PyObject *);
+
+    iternext = *Py_TYPE(it)->tp_iternext;
+    for (;;) {
+        item = iternext(it);
+        if (item == NULL)
+            return NULL;
+        if (lz->start == 1)
+            return item;
+
+        good = PyObject_CallFunctionObjArgs(lz->func, item, NULL);
+        if (good == NULL) {
+            Py_DECREF(item);
+            return NULL;
+        }
+        ok = PyObject_IsTrue(good);
+        Py_DECREF(good);
+        if (!ok) {
+            lz->start = 1;
+            return item;
+        }
+        Py_DECREF(item);
+    }
+}
+
+PyDoc_STRVAR(dropwhile_doc,
+"dropwhile(predicate, iterable) --> dropwhile object\n\
+\n\
+Drop items from the iterable while predicate(item) is true.\n\
+Afterwards, return every element until the iterable is exhausted.");
+
+static PyTypeObject dropwhile_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.dropwhile",              /* tp_name */
+    sizeof(dropwhileobject),            /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)dropwhile_dealloc,      /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    dropwhile_doc,                      /* tp_doc */
+    (traverseproc)dropwhile_traverse,    /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)dropwhile_next,       /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    dropwhile_new,                      /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* takewhile object **********************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *func;
+    PyObject *it;
+    long         stop;
+} takewhileobject;
+
+static PyTypeObject takewhile_type;
+
+static PyObject *
+takewhile_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    PyObject *func, *seq;
+    PyObject *it;
+    takewhileobject *lz;
+
+    if (type == &takewhile_type && !_PyArg_NoKeywords("takewhile()", kwds))
+        return NULL;
+
+    if (!PyArg_UnpackTuple(args, "takewhile", 2, 2, &func, &seq))
+        return NULL;
+
+    /* Get iterator. */
+    it = PyObject_GetIter(seq);
+    if (it == NULL)
+        return NULL;
+
+    /* create takewhileobject structure */
+    lz = (takewhileobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_DECREF(it);
+        return NULL;
+    }
+    Py_INCREF(func);
+    lz->func = func;
+    lz->it = it;
+    lz->stop = 0;
+
+    return (PyObject *)lz;
+}
+
+static void
+takewhile_dealloc(takewhileobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->func);
+    Py_XDECREF(lz->it);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+takewhile_traverse(takewhileobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->it);
+    Py_VISIT(lz->func);
+    return 0;
+}
+
+static PyObject *
+takewhile_next(takewhileobject *lz)
+{
+    PyObject *item, *good;
+    PyObject *it = lz->it;
+    long ok;
+
+    if (lz->stop == 1)
+        return NULL;
+
+    item = (*Py_TYPE(it)->tp_iternext)(it);
+    if (item == NULL)
+        return NULL;
+
+    good = PyObject_CallFunctionObjArgs(lz->func, item, NULL);
+    if (good == NULL) {
+        Py_DECREF(item);
+        return NULL;
+    }
+    ok = PyObject_IsTrue(good);
+    Py_DECREF(good);
+    if (ok)
+        return item;
+    Py_DECREF(item);
+    lz->stop = 1;
+    return NULL;
+}
+
+PyDoc_STRVAR(takewhile_doc,
+"takewhile(predicate, iterable) --> takewhile object\n\
+\n\
+Return successive entries from an iterable as long as the \n\
+predicate evaluates to true for each entry.");
+
+static PyTypeObject takewhile_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.takewhile",              /* tp_name */
+    sizeof(takewhileobject),            /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)takewhile_dealloc,      /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    takewhile_doc,                      /* tp_doc */
+    (traverseproc)takewhile_traverse,    /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)takewhile_next,       /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    takewhile_new,                      /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* islice object ************************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *it;
+    Py_ssize_t next;
+    Py_ssize_t stop;
+    Py_ssize_t step;
+    Py_ssize_t cnt;
+} isliceobject;
+
+static PyTypeObject islice_type;
+
+static PyObject *
+islice_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    PyObject *seq;
+    Py_ssize_t start=0, stop=-1, step=1;
+    PyObject *it, *a1=NULL, *a2=NULL, *a3=NULL;
+    Py_ssize_t numargs;
+    isliceobject *lz;
+
+    if (type == &islice_type && !_PyArg_NoKeywords("islice()", kwds))
+        return NULL;
+
+    if (!PyArg_UnpackTuple(args, "islice", 2, 4, &seq, &a1, &a2, &a3))
+        return NULL;
+
+    numargs = PyTuple_Size(args);
+    if (numargs == 2) {
+        if (a1 != Py_None) {
+            stop = PyInt_AsSsize_t(a1);
+            if (stop == -1) {
+                if (PyErr_Occurred())
+                    PyErr_Clear();
+                PyErr_SetString(PyExc_ValueError,
+                    "Stop argument for islice() must be None or an integer: 0 <= x <= maxint.");
+                return NULL;
+            }
+        }
+    } else {
+        if (a1 != Py_None)
+            start = PyInt_AsSsize_t(a1);
+        if (start == -1 && PyErr_Occurred())
+            PyErr_Clear();
+        if (a2 != Py_None) {
+            stop = PyInt_AsSsize_t(a2);
+            if (stop == -1) {
+                if (PyErr_Occurred())
+                    PyErr_Clear();
+                PyErr_SetString(PyExc_ValueError,
+                   "Stop argument for islice() must be None or an integer: 0 <= x <= maxint.");
+                return NULL;
+            }
+        }
+    }
+    if (start<0 || stop<-1) {
+        PyErr_SetString(PyExc_ValueError,
+           "Indices for islice() must be None or an integer: 0 <= x <= maxint.");
+        return NULL;
+    }
+
+    if (a3 != NULL) {
+        if (a3 != Py_None)
+            step = PyInt_AsSsize_t(a3);
+        if (step == -1 && PyErr_Occurred())
+            PyErr_Clear();
+    }
+    if (step<1) {
+        PyErr_SetString(PyExc_ValueError,
+           "Step for islice() must be a positive integer or None.");
+        return NULL;
+    }
+
+    /* Get iterator. */
+    it = PyObject_GetIter(seq);
+    if (it == NULL)
+        return NULL;
+
+    /* create isliceobject structure */
+    lz = (isliceobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_DECREF(it);
+        return NULL;
+    }
+    lz->it = it;
+    lz->next = start;
+    lz->stop = stop;
+    lz->step = step;
+    lz->cnt = 0L;
+
+    return (PyObject *)lz;
+}
+
+static void
+islice_dealloc(isliceobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->it);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+islice_traverse(isliceobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->it);
+    return 0;
+}
+
+static PyObject *
+islice_next(isliceobject *lz)
+{
+    PyObject *item;
+    PyObject *it = lz->it;
+    Py_ssize_t stop = lz->stop;
+    Py_ssize_t oldnext;
+    PyObject *(*iternext)(PyObject *);
+
+    iternext = *Py_TYPE(it)->tp_iternext;
+    while (lz->cnt < lz->next) {
+        item = iternext(it);
+        if (item == NULL)
+            return NULL;
+        Py_DECREF(item);
+        lz->cnt++;
+    }
+    if (stop != -1 && lz->cnt >= stop)
+        return NULL;
+    item = iternext(it);
+    if (item == NULL)
+        return NULL;
+    lz->cnt++;
+    oldnext = lz->next;
+    lz->next += lz->step;
+    if (lz->next < oldnext || (stop != -1 && lz->next > stop))
+        lz->next = stop;
+    return item;
+}
+
+PyDoc_STRVAR(islice_doc,
+"islice(iterable, [start,] stop [, step]) --> islice object\n\
+\n\
+Return an iterator whose next() method returns selected values from an\n\
+iterable.  If start is specified, will skip all preceding elements;\n\
+otherwise, start defaults to zero.  Step defaults to one.  If\n\
+specified as another value, step determines how many values are \n\
+skipped between successive calls.  Works like a slice() on a list\n\
+but returns an iterator.");
+
+static PyTypeObject islice_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.islice",                 /* tp_name */
+    sizeof(isliceobject),               /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)islice_dealloc,         /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    islice_doc,                         /* tp_doc */
+    (traverseproc)islice_traverse,      /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)islice_next,          /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    islice_new,                         /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* starmap object ************************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *func;
+    PyObject *it;
+} starmapobject;
+
+static PyTypeObject starmap_type;
+
+static PyObject *
+starmap_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    PyObject *func, *seq;
+    PyObject *it;
+    starmapobject *lz;
+
+    if (type == &starmap_type && !_PyArg_NoKeywords("starmap()", kwds))
+        return NULL;
+
+    if (!PyArg_UnpackTuple(args, "starmap", 2, 2, &func, &seq))
+        return NULL;
+
+    /* Get iterator. */
+    it = PyObject_GetIter(seq);
+    if (it == NULL)
+        return NULL;
+
+    /* create starmapobject structure */
+    lz = (starmapobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_DECREF(it);
+        return NULL;
+    }
+    Py_INCREF(func);
+    lz->func = func;
+    lz->it = it;
+
+    return (PyObject *)lz;
+}
+
+static void
+starmap_dealloc(starmapobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->func);
+    Py_XDECREF(lz->it);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+starmap_traverse(starmapobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->it);
+    Py_VISIT(lz->func);
+    return 0;
+}
+
+static PyObject *
+starmap_next(starmapobject *lz)
+{
+    PyObject *args;
+    PyObject *result;
+    PyObject *it = lz->it;
+
+    args = (*Py_TYPE(it)->tp_iternext)(it);
+    if (args == NULL)
+        return NULL;
+    if (!PyTuple_CheckExact(args)) {
+        PyObject *newargs = PySequence_Tuple(args);
+        Py_DECREF(args);
+        if (newargs == NULL)
+            return NULL;
+        args = newargs;
+    }
+    result = PyObject_Call(lz->func, args, NULL);
+    Py_DECREF(args);
+    return result;
+}
+
+PyDoc_STRVAR(starmap_doc,
+"starmap(function, sequence) --> starmap object\n\
+\n\
+Return an iterator whose values are returned from the function evaluated\n\
+with a argument tuple taken from the given sequence.");
+
+static PyTypeObject starmap_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.starmap",                /* tp_name */
+    sizeof(starmapobject),              /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)starmap_dealloc,        /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    starmap_doc,                        /* tp_doc */
+    (traverseproc)starmap_traverse,     /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)starmap_next,         /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    starmap_new,                        /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* imap object ************************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *iters;
+    PyObject *func;
+} imapobject;
+
+static PyTypeObject imap_type;
+
+static PyObject *
+imap_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    PyObject *it, *iters, *func;
+    imapobject *lz;
+    Py_ssize_t numargs, i;
+
+    if (type == &imap_type && !_PyArg_NoKeywords("imap()", kwds))
+        return NULL;
+
+    numargs = PyTuple_Size(args);
+    if (numargs < 2) {
+        PyErr_SetString(PyExc_TypeError,
+           "imap() must have at least two arguments.");
+        return NULL;
+    }
+
+    iters = PyTuple_New(numargs-1);
+    if (iters == NULL)
+        return NULL;
+
+    for (i=1 ; i<numargs ; i++) {
+        /* Get iterator. */
+        it = PyObject_GetIter(PyTuple_GET_ITEM(args, i));
+        if (it == NULL) {
+            Py_DECREF(iters);
+            return NULL;
+        }
+        PyTuple_SET_ITEM(iters, i-1, it);
+    }
+
+    /* create imapobject structure */
+    lz = (imapobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_DECREF(iters);
+        return NULL;
+    }
+    lz->iters = iters;
+    func = PyTuple_GET_ITEM(args, 0);
+    Py_INCREF(func);
+    lz->func = func;
+
+    return (PyObject *)lz;
+}
+
+static void
+imap_dealloc(imapobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->iters);
+    Py_XDECREF(lz->func);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+imap_traverse(imapobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->iters);
+    Py_VISIT(lz->func);
+    return 0;
+}
+
+/*
+imap() is an iterator version of __builtins__.map() except that it does
+not have the None fill-in feature.  That was intentionally left out for
+the following reasons:
+
+  1) Itertools are designed to be easily combined and chained together.
+     Having all tools stop with the shortest input is a unifying principle
+     that makes it easier to combine finite iterators (supplying data) with
+     infinite iterators like count() and repeat() (for supplying sequential
+     or constant arguments to a function).
+
+  2) In typical use cases for combining itertools, having one finite data
+     supplier run out before another is likely to be an error condition which
+     should not pass silently by automatically supplying None.
+
+  3) The use cases for automatic None fill-in are rare -- not many functions
+     do something useful when a parameter suddenly switches type and becomes
+     None.
+
+  4) If a need does arise, it can be met by __builtins__.map() or by
+     writing:  chain(iterable, repeat(None)).
+
+  5) Similar toolsets in Haskell and SML do not have automatic None fill-in.
+*/
+
+static PyObject *
+imap_next(imapobject *lz)
+{
+    PyObject *val;
+    PyObject *argtuple;
+    PyObject *result;
+    Py_ssize_t numargs, i;
+
+    numargs = PyTuple_Size(lz->iters);
+    argtuple = PyTuple_New(numargs);
+    if (argtuple == NULL)
+        return NULL;
+
+    for (i=0 ; i<numargs ; i++) {
+        val = PyIter_Next(PyTuple_GET_ITEM(lz->iters, i));
+        if (val == NULL) {
+            Py_DECREF(argtuple);
+            return NULL;
+        }
+        PyTuple_SET_ITEM(argtuple, i, val);
+    }
+    if (lz->func == Py_None)
+        return argtuple;
+    result = PyObject_Call(lz->func, argtuple, NULL);
+    Py_DECREF(argtuple);
+    return result;
+}
+
+PyDoc_STRVAR(imap_doc,
+"imap(func, *iterables) --> imap object\n\
+\n\
+Make an iterator that computes the function using arguments from\n\
+each of the iterables.  Like map() except that it returns\n\
+an iterator instead of a list and that it stops when the shortest\n\
+iterable is exhausted instead of filling in None for shorter\n\
+iterables.");
+
+static PyTypeObject imap_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.imap",                   /* tp_name */
+    sizeof(imapobject),                 /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)imap_dealloc,           /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    imap_doc,                           /* tp_doc */
+    (traverseproc)imap_traverse,        /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)imap_next,            /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    imap_new,                           /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* chain object ************************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *source;                   /* Iterator over input iterables */
+    PyObject *active;                   /* Currently running input iterator */
+} chainobject;
+
+static PyTypeObject chain_type;
+
+static PyObject *
+chain_new_internal(PyTypeObject *type, PyObject *source)
+{
+    chainobject *lz;
+
+    lz = (chainobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_DECREF(source);
+        return NULL;
+    }
+
+    lz->source = source;
+    lz->active = NULL;
+    return (PyObject *)lz;
+}
+
+static PyObject *
+chain_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    PyObject *source;
+
+    if (type == &chain_type && !_PyArg_NoKeywords("chain()", kwds))
+        return NULL;
+
+    source = PyObject_GetIter(args);
+    if (source == NULL)
+        return NULL;
+
+    return chain_new_internal(type, source);
+}
+
+static PyObject *
+chain_new_from_iterable(PyTypeObject *type, PyObject *arg)
+{
+    PyObject *source;
+
+    source = PyObject_GetIter(arg);
+    if (source == NULL)
+        return NULL;
+
+    return chain_new_internal(type, source);
+}
+
+static void
+chain_dealloc(chainobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->active);
+    Py_XDECREF(lz->source);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+chain_traverse(chainobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->source);
+    Py_VISIT(lz->active);
+    return 0;
+}
+
+static PyObject *
+chain_next(chainobject *lz)
+{
+    PyObject *item;
+
+    if (lz->source == NULL)
+        return NULL;                                    /* already stopped */
+
+    if (lz->active == NULL) {
+        PyObject *iterable = PyIter_Next(lz->source);
+        if (iterable == NULL) {
+            Py_CLEAR(lz->source);
+            return NULL;                                /* no more input sources */
+        }
+        lz->active = PyObject_GetIter(iterable);
+        Py_DECREF(iterable);
+        if (lz->active == NULL) {
+            Py_CLEAR(lz->source);
+            return NULL;                                /* input not iterable */
+        }
+    }
+    item = PyIter_Next(lz->active);
+    if (item != NULL)
+        return item;
+    if (PyErr_Occurred()) {
+        if (PyErr_ExceptionMatches(PyExc_StopIteration))
+            PyErr_Clear();
+        else
+            return NULL;                                /* input raised an exception */
+    }
+    Py_CLEAR(lz->active);
+    return chain_next(lz);                      /* recurse and use next active */
+}
+
+PyDoc_STRVAR(chain_doc,
+"chain(*iterables) --> chain object\n\
+\n\
+Return a chain object whose .next() method returns elements from the\n\
+first iterable until it is exhausted, then elements from the next\n\
+iterable, until all of the iterables are exhausted.");
+
+PyDoc_STRVAR(chain_from_iterable_doc,
+"chain.from_iterable(iterable) --> chain object\n\
+\n\
+Alternate chain() contructor taking a single iterable argument\n\
+that evaluates lazily.");
+
+static PyMethodDef chain_methods[] = {
+    {"from_iterable", (PyCFunction) chain_new_from_iterable,            METH_O | METH_CLASS,
+        chain_from_iterable_doc},
+    {NULL,              NULL}   /* sentinel */
+};
+
+static PyTypeObject chain_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.chain",                  /* tp_name */
+    sizeof(chainobject),                /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)chain_dealloc,          /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    chain_doc,                          /* tp_doc */
+    (traverseproc)chain_traverse,       /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)chain_next,           /* tp_iternext */
+    chain_methods,                      /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    chain_new,                          /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* product object ************************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *pools;                    /* tuple of pool tuples */
+    Py_ssize_t *indices;            /* one index per pool */
+    PyObject *result;               /* most recently returned result tuple */
+    int stopped;                    /* set to 1 when the product iterator is exhausted */
+} productobject;
+
+static PyTypeObject product_type;
+
+static PyObject *
+product_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    productobject *lz;
+    Py_ssize_t nargs, npools, repeat=1;
+    PyObject *pools = NULL;
+    Py_ssize_t *indices = NULL;
+    Py_ssize_t i;
+
+    if (kwds != NULL) {
+        char *kwlist[] = {"repeat", 0};
+        PyObject *tmpargs = PyTuple_New(0);
+        if (tmpargs == NULL)
+            return NULL;
+        if (!PyArg_ParseTupleAndKeywords(tmpargs, kwds, "|n:product", kwlist, &repeat)) {
+            Py_DECREF(tmpargs);
+            return NULL;
+        }
+        Py_DECREF(tmpargs);
+        if (repeat < 0) {
+            PyErr_SetString(PyExc_ValueError,
+                            "repeat argument cannot be negative");
+            return NULL;
+        }
+    }
+
+    assert(PyTuple_Check(args));
+    nargs = (repeat == 0) ? 0 : PyTuple_GET_SIZE(args);
+    npools = nargs * repeat;
+
+    indices = PyMem_Malloc(npools * sizeof(Py_ssize_t));
+    if (indices == NULL) {
+        PyErr_NoMemory();
+        goto error;
+    }
+
+    pools = PyTuple_New(npools);
+    if (pools == NULL)
+        goto error;
+
+    for (i=0; i < nargs ; ++i) {
+        PyObject *item = PyTuple_GET_ITEM(args, i);
+        PyObject *pool = PySequence_Tuple(item);
+        if (pool == NULL)
+            goto error;
+        PyTuple_SET_ITEM(pools, i, pool);
+        indices[i] = 0;
+    }
+    for ( ; i < npools; ++i) {
+        PyObject *pool = PyTuple_GET_ITEM(pools, i - nargs);
+        Py_INCREF(pool);
+        PyTuple_SET_ITEM(pools, i, pool);
+        indices[i] = 0;
+    }
+
+    /* create productobject structure */
+    lz = (productobject *)type->tp_alloc(type, 0);
+    if (lz == NULL)
+        goto error;
+
+    lz->pools = pools;
+    lz->indices = indices;
+    lz->result = NULL;
+    lz->stopped = 0;
+
+    return (PyObject *)lz;
+
+error:
+    if (indices != NULL)
+        PyMem_Free(indices);
+    Py_XDECREF(pools);
+    return NULL;
+}
+
+static void
+product_dealloc(productobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->pools);
+    Py_XDECREF(lz->result);
+    if (lz->indices != NULL)
+        PyMem_Free(lz->indices);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+product_traverse(productobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->pools);
+    Py_VISIT(lz->result);
+    return 0;
+}
+
+static PyObject *
+product_next(productobject *lz)
+{
+    PyObject *pool;
+    PyObject *elem;
+    PyObject *oldelem;
+    PyObject *pools = lz->pools;
+    PyObject *result = lz->result;
+    Py_ssize_t npools = PyTuple_GET_SIZE(pools);
+    Py_ssize_t i;
+
+    if (lz->stopped)
+        return NULL;
+
+    if (result == NULL) {
+        /* On the first pass, return an initial tuple filled with the
+           first element from each pool. */
+        result = PyTuple_New(npools);
+        if (result == NULL)
+            goto empty;
+        lz->result = result;
+        for (i=0; i < npools; i++) {
+            pool = PyTuple_GET_ITEM(pools, i);
+            if (PyTuple_GET_SIZE(pool) == 0)
+                goto empty;
+            elem = PyTuple_GET_ITEM(pool, 0);
+            Py_INCREF(elem);
+            PyTuple_SET_ITEM(result, i, elem);
+        }
+    } else {
+        Py_ssize_t *indices = lz->indices;
+
+        /* Copy the previous result tuple or re-use it if available */
+        if (Py_REFCNT(result) > 1) {
+            PyObject *old_result = result;
+            result = PyTuple_New(npools);
+            if (result == NULL)
+                goto empty;
+            lz->result = result;
+            for (i=0; i < npools; i++) {
+                elem = PyTuple_GET_ITEM(old_result, i);
+                Py_INCREF(elem);
+                PyTuple_SET_ITEM(result, i, elem);
+            }
+            Py_DECREF(old_result);
+        }
+        /* Now, we've got the only copy so we can update it in-place */
+        assert (npools==0 || Py_REFCNT(result) == 1);
+
+        /* Update the pool indices right-to-left.  Only advance to the
+           next pool when the previous one rolls-over */
+        for (i=npools-1 ; i >= 0 ; i--) {
+            pool = PyTuple_GET_ITEM(pools, i);
+            indices[i]++;
+            if (indices[i] == PyTuple_GET_SIZE(pool)) {
+                /* Roll-over and advance to next pool */
+                indices[i] = 0;
+                elem = PyTuple_GET_ITEM(pool, 0);
+                Py_INCREF(elem);
+                oldelem = PyTuple_GET_ITEM(result, i);
+                PyTuple_SET_ITEM(result, i, elem);
+                Py_DECREF(oldelem);
+            } else {
+                /* No rollover. Just increment and stop here. */
+                elem = PyTuple_GET_ITEM(pool, indices[i]);
+                Py_INCREF(elem);
+                oldelem = PyTuple_GET_ITEM(result, i);
+                PyTuple_SET_ITEM(result, i, elem);
+                Py_DECREF(oldelem);
+                break;
+            }
+        }
+
+        /* If i is negative, then the indices have all rolled-over
+           and we're done. */
+        if (i < 0)
+            goto empty;
+    }
+
+    Py_INCREF(result);
+    return result;
+
+empty:
+    lz->stopped = 1;
+    return NULL;
+}
+
+PyDoc_STRVAR(product_doc,
+"product(*iterables) --> product object\n\
+\n\
+Cartesian product of input iterables.  Equivalent to nested for-loops.\n\n\
+For example, product(A, B) returns the same as:  ((x,y) for x in A for y in B).\n\
+The leftmost iterators are in the outermost for-loop, so the output tuples\n\
+cycle in a manner similar to an odometer (with the rightmost element changing\n\
+on every iteration).\n\n\
+To compute the product of an iterable with itself, specify the number\n\
+of repetitions with the optional repeat keyword argument. For example,\n\
+product(A, repeat=4) means the same as product(A, A, A, A).\n\n\
+product('ab', range(3)) --> ('a',0) ('a',1) ('a',2) ('b',0) ('b',1) ('b',2)\n\
+product((0,1), (0,1), (0,1)) --> (0,0,0) (0,0,1) (0,1,0) (0,1,1) (1,0,0) ...");
+
+static PyTypeObject product_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.product",                /* tp_name */
+    sizeof(productobject),      /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)product_dealloc,        /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    product_doc,                        /* tp_doc */
+    (traverseproc)product_traverse,     /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)product_next,         /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    product_new,                        /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* combinations object ************************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *pool;                     /* input converted to a tuple */
+    Py_ssize_t *indices;            /* one index per result element */
+    PyObject *result;               /* most recently returned result tuple */
+    Py_ssize_t r;                       /* size of result tuple */
+    int stopped;                        /* set to 1 when the combinations iterator is exhausted */
+} combinationsobject;
+
+static PyTypeObject combinations_type;
+
+static PyObject *
+combinations_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    combinationsobject *co;
+    Py_ssize_t n;
+    Py_ssize_t r;
+    PyObject *pool = NULL;
+    PyObject *iterable = NULL;
+    Py_ssize_t *indices = NULL;
+    Py_ssize_t i;
+    static char *kwargs[] = {"iterable", "r", NULL};
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "On:combinations", kwargs,
+                                     &iterable, &r))
+        return NULL;
+
+    pool = PySequence_Tuple(iterable);
+    if (pool == NULL)
+        goto error;
+    n = PyTuple_GET_SIZE(pool);
+    if (r < 0) {
+        PyErr_SetString(PyExc_ValueError, "r must be non-negative");
+        goto error;
+    }
+
+    indices = PyMem_Malloc(r * sizeof(Py_ssize_t));
+    if (indices == NULL) {
+        PyErr_NoMemory();
+        goto error;
+    }
+
+    for (i=0 ; i<r ; i++)
+        indices[i] = i;
+
+    /* create combinationsobject structure */
+    co = (combinationsobject *)type->tp_alloc(type, 0);
+    if (co == NULL)
+        goto error;
+
+    co->pool = pool;
+    co->indices = indices;
+    co->result = NULL;
+    co->r = r;
+    co->stopped = r > n ? 1 : 0;
+
+    return (PyObject *)co;
+
+error:
+    if (indices != NULL)
+        PyMem_Free(indices);
+    Py_XDECREF(pool);
+    return NULL;
+}
+
+static void
+combinations_dealloc(combinationsobject *co)
+{
+    PyObject_GC_UnTrack(co);
+    Py_XDECREF(co->pool);
+    Py_XDECREF(co->result);
+    if (co->indices != NULL)
+        PyMem_Free(co->indices);
+    Py_TYPE(co)->tp_free(co);
+}
+
+static int
+combinations_traverse(combinationsobject *co, visitproc visit, void *arg)
+{
+    Py_VISIT(co->pool);
+    Py_VISIT(co->result);
+    return 0;
+}
+
+static PyObject *
+combinations_next(combinationsobject *co)
+{
+    PyObject *elem;
+    PyObject *oldelem;
+    PyObject *pool = co->pool;
+    Py_ssize_t *indices = co->indices;
+    PyObject *result = co->result;
+    Py_ssize_t n = PyTuple_GET_SIZE(pool);
+    Py_ssize_t r = co->r;
+    Py_ssize_t i, j, index;
+
+    if (co->stopped)
+        return NULL;
+
+    if (result == NULL) {
+        /* On the first pass, initialize result tuple using the indices */
+        result = PyTuple_New(r);
+        if (result == NULL)
+            goto empty;
+        co->result = result;
+        for (i=0; i<r ; i++) {
+            index = indices[i];
+            elem = PyTuple_GET_ITEM(pool, index);
+            Py_INCREF(elem);
+            PyTuple_SET_ITEM(result, i, elem);
+        }
+    } else {
+        /* Copy the previous result tuple or re-use it if available */
+        if (Py_REFCNT(result) > 1) {
+            PyObject *old_result = result;
+            result = PyTuple_New(r);
+            if (result == NULL)
+                goto empty;
+            co->result = result;
+            for (i=0; i<r ; i++) {
+                elem = PyTuple_GET_ITEM(old_result, i);
+                Py_INCREF(elem);
+                PyTuple_SET_ITEM(result, i, elem);
+            }
+            Py_DECREF(old_result);
+        }
+        /* Now, we've got the only copy so we can update it in-place
+         * CPython's empty tuple is a singleton and cached in
+         * PyTuple's freelist.
+         */
+        assert(r == 0 || Py_REFCNT(result) == 1);
+
+        /* Scan indices right-to-left until finding one that is not
+           at its maximum (i + n - r). */
+        for (i=r-1 ; i >= 0 && indices[i] == i+n-r ; i--)
+            ;
+
+        /* If i is negative, then the indices are all at
+           their maximum value and we're done. */
+        if (i < 0)
+            goto empty;
+
+        /* Increment the current index which we know is not at its
+           maximum.  Then move back to the right setting each index
+           to its lowest possible value (one higher than the index
+           to its left -- this maintains the sort order invariant). */
+        indices[i]++;
+        for (j=i+1 ; j<r ; j++)
+            indices[j] = indices[j-1] + 1;
+
+        /* Update the result tuple for the new indices
+           starting with i, the leftmost index that changed */
+        for ( ; i<r ; i++) {
+            index = indices[i];
+            elem = PyTuple_GET_ITEM(pool, index);
+            Py_INCREF(elem);
+            oldelem = PyTuple_GET_ITEM(result, i);
+            PyTuple_SET_ITEM(result, i, elem);
+            Py_DECREF(oldelem);
+        }
+    }
+
+    Py_INCREF(result);
+    return result;
+
+empty:
+    co->stopped = 1;
+    return NULL;
+}
+
+PyDoc_STRVAR(combinations_doc,
+"combinations(iterable, r) --> combinations object\n\
+\n\
+Return successive r-length combinations of elements in the iterable.\n\n\
+combinations(range(4), 3) --> (0,1,2), (0,1,3), (0,2,3), (1,2,3)");
+
+static PyTypeObject combinations_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.combinations",                   /* tp_name */
+    sizeof(combinationsobject),         /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)combinations_dealloc,           /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    combinations_doc,                           /* tp_doc */
+    (traverseproc)combinations_traverse,        /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)combinations_next,            /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    combinations_new,                           /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* combinations with replacement object *******************************************/
+
+/* Equivalent to:
+
+        def combinations_with_replacement(iterable, r):
+            "combinations_with_replacement('ABC', 2) --> AA AB AC BB BC CC"
+            # number items returned:  (n+r-1)! / r! / (n-1)!
+            pool = tuple(iterable)
+            n = len(pool)
+            indices = [0] * r
+            yield tuple(pool[i] for i in indices)
+            while 1:
+                for i in reversed(range(r)):
+                    if indices[i] != n - 1:
+                        break
+                else:
+                    return
+                indices[i:] = [indices[i] + 1] * (r - i)
+                yield tuple(pool[i] for i in indices)
+
+        def combinations_with_replacement2(iterable, r):
+            'Alternate version that filters from product()'
+            pool = tuple(iterable)
+            n = len(pool)
+            for indices in product(range(n), repeat=r):
+                if sorted(indices) == list(indices):
+                    yield tuple(pool[i] for i in indices)
+*/
+typedef struct {
+    PyObject_HEAD
+    PyObject *pool;                     /* input converted to a tuple */
+    Py_ssize_t *indices;    /* one index per result element */
+    PyObject *result;       /* most recently returned result tuple */
+    Py_ssize_t r;                       /* size of result tuple */
+    int stopped;                        /* set to 1 when the cwr iterator is exhausted */
+} cwrobject;
+
+static PyTypeObject cwr_type;
+
+static PyObject *
+cwr_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    cwrobject *co;
+    Py_ssize_t n;
+    Py_ssize_t r;
+    PyObject *pool = NULL;
+    PyObject *iterable = NULL;
+    Py_ssize_t *indices = NULL;
+    Py_ssize_t i;
+    static char *kwargs[] = {"iterable", "r", NULL};
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "On:combinations_with_replacement", kwargs,
+                                     &iterable, &r))
+        return NULL;
+
+    pool = PySequence_Tuple(iterable);
+    if (pool == NULL)
+        goto error;
+    n = PyTuple_GET_SIZE(pool);
+    if (r < 0) {
+        PyErr_SetString(PyExc_ValueError, "r must be non-negative");
+        goto error;
+    }
+
+    indices = PyMem_Malloc(r * sizeof(Py_ssize_t));
+    if (indices == NULL) {
+        PyErr_NoMemory();
+        goto error;
+    }
+
+    for (i=0 ; i<r ; i++)
+        indices[i] = 0;
+
+    /* create cwrobject structure */
+    co = (cwrobject *)type->tp_alloc(type, 0);
+    if (co == NULL)
+        goto error;
+
+    co->pool = pool;
+    co->indices = indices;
+    co->result = NULL;
+    co->r = r;
+    co->stopped = !n && r;
+
+    return (PyObject *)co;
+
+error:
+    if (indices != NULL)
+        PyMem_Free(indices);
+    Py_XDECREF(pool);
+    return NULL;
+}
+
+static void
+cwr_dealloc(cwrobject *co)
+{
+    PyObject_GC_UnTrack(co);
+    Py_XDECREF(co->pool);
+    Py_XDECREF(co->result);
+    if (co->indices != NULL)
+        PyMem_Free(co->indices);
+    Py_TYPE(co)->tp_free(co);
+}
+
+static int
+cwr_traverse(cwrobject *co, visitproc visit, void *arg)
+{
+    Py_VISIT(co->pool);
+    Py_VISIT(co->result);
+    return 0;
+}
+
+static PyObject *
+cwr_next(cwrobject *co)
+{
+    PyObject *elem;
+    PyObject *oldelem;
+    PyObject *pool = co->pool;
+    Py_ssize_t *indices = co->indices;
+    PyObject *result = co->result;
+    Py_ssize_t n = PyTuple_GET_SIZE(pool);
+    Py_ssize_t r = co->r;
+    Py_ssize_t i, j, index;
+
+    if (co->stopped)
+        return NULL;
+
+    if (result == NULL) {
+        /* On the first pass, initialize result tuple using the indices */
+        result = PyTuple_New(r);
+        if (result == NULL)
+            goto empty;
+        co->result = result;
+        for (i=0; i<r ; i++) {
+            index = indices[i];
+            elem = PyTuple_GET_ITEM(pool, index);
+            Py_INCREF(elem);
+            PyTuple_SET_ITEM(result, i, elem);
+        }
+    } else {
+        /* Copy the previous result tuple or re-use it if available */
+        if (Py_REFCNT(result) > 1) {
+            PyObject *old_result = result;
+            result = PyTuple_New(r);
+            if (result == NULL)
+                goto empty;
+            co->result = result;
+            for (i=0; i<r ; i++) {
+                elem = PyTuple_GET_ITEM(old_result, i);
+                Py_INCREF(elem);
+                PyTuple_SET_ITEM(result, i, elem);
+            }
+            Py_DECREF(old_result);
+        }
+        /* Now, we've got the only copy so we can update it in-place CPython's
+           empty tuple is a singleton and cached in PyTuple's freelist. */
+        assert(r == 0 || Py_REFCNT(result) == 1);
+
+    /* Scan indices right-to-left until finding one that is not
+     * at its maximum (n-1). */
+        for (i=r-1 ; i >= 0 && indices[i] == n-1; i--)
+            ;
+
+        /* If i is negative, then the indices are all at
+       their maximum value and we're done. */
+        if (i < 0)
+            goto empty;
+
+        /* Increment the current index which we know is not at its
+       maximum.  Then set all to the right to the same value. */
+        indices[i]++;
+        for (j=i+1 ; j<r ; j++)
+            indices[j] = indices[j-1];
+
+        /* Update the result tuple for the new indices
+           starting with i, the leftmost index that changed */
+        for ( ; i<r ; i++) {
+            index = indices[i];
+            elem = PyTuple_GET_ITEM(pool, index);
+            Py_INCREF(elem);
+            oldelem = PyTuple_GET_ITEM(result, i);
+            PyTuple_SET_ITEM(result, i, elem);
+            Py_DECREF(oldelem);
+        }
+    }
+
+    Py_INCREF(result);
+    return result;
+
+empty:
+    co->stopped = 1;
+    return NULL;
+}
+
+PyDoc_STRVAR(cwr_doc,
+"combinations_with_replacement(iterable, r) --> combinations_with_replacement object\n\
+\n\
+Return successive r-length combinations of elements in the iterable\n\
+allowing individual elements to have successive repeats.\n\
+combinations_with_replacement('ABC', 2) --> AA AB AC BB BC CC");
+
+static PyTypeObject cwr_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.combinations_with_replacement",                  /* tp_name */
+    sizeof(cwrobject),                  /* tp_basicsize */
+    0,                                                  /* tp_itemsize */
+    /* methods */
+    (destructor)cwr_dealloc,            /* tp_dealloc */
+    0,                                                  /* tp_print */
+    0,                                                  /* tp_getattr */
+    0,                                                  /* tp_setattr */
+    0,                                                  /* tp_compare */
+    0,                                                  /* tp_repr */
+    0,                                                  /* tp_as_number */
+    0,                                                  /* tp_as_sequence */
+    0,                                                  /* tp_as_mapping */
+    0,                                                  /* tp_hash */
+    0,                                                  /* tp_call */
+    0,                                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                                  /* tp_setattro */
+    0,                                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    cwr_doc,                                    /* tp_doc */
+    (traverseproc)cwr_traverse,         /* tp_traverse */
+    0,                                                  /* tp_clear */
+    0,                                                  /* tp_richcompare */
+    0,                                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)cwr_next,     /* tp_iternext */
+    0,                                                  /* tp_methods */
+    0,                                                  /* tp_members */
+    0,                                                  /* tp_getset */
+    0,                                                  /* tp_base */
+    0,                                                  /* tp_dict */
+    0,                                                  /* tp_descr_get */
+    0,                                                  /* tp_descr_set */
+    0,                                                  /* tp_dictoffset */
+    0,                                                  /* tp_init */
+    0,                                                  /* tp_alloc */
+    cwr_new,                                    /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* permutations object ************************************************************
+
+def permutations(iterable, r=None):
+    'permutations(range(3), 2) --> (0,1) (0,2) (1,0) (1,2) (2,0) (2,1)'
+    pool = tuple(iterable)
+    n = len(pool)
+    r = n if r is None else r
+    indices = range(n)
+    cycles = range(n-r+1, n+1)[::-1]
+    yield tuple(pool[i] for i in indices[:r])
+    while n:
+    for i in reversed(range(r)):
+        cycles[i] -= 1
+        if cycles[i] == 0:
+        indices[i:] = indices[i+1:] + indices[i:i+1]
+        cycles[i] = n - i
+        else:
+        j = cycles[i]
+        indices[i], indices[-j] = indices[-j], indices[i]
+        yield tuple(pool[i] for i in indices[:r])
+        break
+    else:
+        return
+*/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *pool;                     /* input converted to a tuple */
+    Py_ssize_t *indices;            /* one index per element in the pool */
+    Py_ssize_t *cycles;                 /* one rollover counter per element in the result */
+    PyObject *result;               /* most recently returned result tuple */
+    Py_ssize_t r;                       /* size of result tuple */
+    int stopped;                        /* set to 1 when the permutations iterator is exhausted */
+} permutationsobject;
+
+static PyTypeObject permutations_type;
+
+static PyObject *
+permutations_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    permutationsobject *po;
+    Py_ssize_t n;
+    Py_ssize_t r;
+    PyObject *robj = Py_None;
+    PyObject *pool = NULL;
+    PyObject *iterable = NULL;
+    Py_ssize_t *indices = NULL;
+    Py_ssize_t *cycles = NULL;
+    Py_ssize_t i;
+    static char *kwargs[] = {"iterable", "r", NULL};
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|O:permutations", kwargs,
+                                     &iterable, &robj))
+        return NULL;
+
+    pool = PySequence_Tuple(iterable);
+    if (pool == NULL)
+        goto error;
+    n = PyTuple_GET_SIZE(pool);
+
+    r = n;
+    if (robj != Py_None) {
+        r = PyInt_AsSsize_t(robj);
+        if (r == -1 && PyErr_Occurred())
+            goto error;
+    }
+    if (r < 0) {
+        PyErr_SetString(PyExc_ValueError, "r must be non-negative");
+        goto error;
+    }
+
+    indices = PyMem_Malloc(n * sizeof(Py_ssize_t));
+    cycles = PyMem_Malloc(r * sizeof(Py_ssize_t));
+    if (indices == NULL || cycles == NULL) {
+        PyErr_NoMemory();
+        goto error;
+    }
+
+    for (i=0 ; i<n ; i++)
+        indices[i] = i;
+    for (i=0 ; i<r ; i++)
+        cycles[i] = n - i;
+
+    /* create permutationsobject structure */
+    po = (permutationsobject *)type->tp_alloc(type, 0);
+    if (po == NULL)
+        goto error;
+
+    po->pool = pool;
+    po->indices = indices;
+    po->cycles = cycles;
+    po->result = NULL;
+    po->r = r;
+    po->stopped = r > n ? 1 : 0;
+
+    return (PyObject *)po;
+
+error:
+    if (indices != NULL)
+        PyMem_Free(indices);
+    if (cycles != NULL)
+        PyMem_Free(cycles);
+    Py_XDECREF(pool);
+    return NULL;
+}
+
+static void
+permutations_dealloc(permutationsobject *po)
+{
+    PyObject_GC_UnTrack(po);
+    Py_XDECREF(po->pool);
+    Py_XDECREF(po->result);
+    PyMem_Free(po->indices);
+    PyMem_Free(po->cycles);
+    Py_TYPE(po)->tp_free(po);
+}
+
+static int
+permutations_traverse(permutationsobject *po, visitproc visit, void *arg)
+{
+    Py_VISIT(po->pool);
+    Py_VISIT(po->result);
+    return 0;
+}
+
+static PyObject *
+permutations_next(permutationsobject *po)
+{
+    PyObject *elem;
+    PyObject *oldelem;
+    PyObject *pool = po->pool;
+    Py_ssize_t *indices = po->indices;
+    Py_ssize_t *cycles = po->cycles;
+    PyObject *result = po->result;
+    Py_ssize_t n = PyTuple_GET_SIZE(pool);
+    Py_ssize_t r = po->r;
+    Py_ssize_t i, j, k, index;
+
+    if (po->stopped)
+        return NULL;
+
+    if (result == NULL) {
+        /* On the first pass, initialize result tuple using the indices */
+        result = PyTuple_New(r);
+        if (result == NULL)
+            goto empty;
+        po->result = result;
+        for (i=0; i<r ; i++) {
+            index = indices[i];
+            elem = PyTuple_GET_ITEM(pool, index);
+            Py_INCREF(elem);
+            PyTuple_SET_ITEM(result, i, elem);
+        }
+    } else {
+        if (n == 0)
+            goto empty;
+
+        /* Copy the previous result tuple or re-use it if available */
+        if (Py_REFCNT(result) > 1) {
+            PyObject *old_result = result;
+            result = PyTuple_New(r);
+            if (result == NULL)
+                goto empty;
+            po->result = result;
+            for (i=0; i<r ; i++) {
+                elem = PyTuple_GET_ITEM(old_result, i);
+                Py_INCREF(elem);
+                PyTuple_SET_ITEM(result, i, elem);
+            }
+            Py_DECREF(old_result);
+        }
+        /* Now, we've got the only copy so we can update it in-place */
+        assert(r == 0 || Py_REFCNT(result) == 1);
+
+        /* Decrement rightmost cycle, moving leftward upon zero rollover */
+        for (i=r-1 ; i>=0 ; i--) {
+            cycles[i] -= 1;
+            if (cycles[i] == 0) {
+                /* rotatation: indices[i:] = indices[i+1:] + indices[i:i+1] */
+                index = indices[i];
+                for (j=i ; j<n-1 ; j++)
+                    indices[j] = indices[j+1];
+                indices[n-1] = index;
+                cycles[i] = n - i;
+            } else {
+                j = cycles[i];
+                index = indices[i];
+                indices[i] = indices[n-j];
+                indices[n-j] = index;
+
+                for (k=i; k<r ; k++) {
+                    /* start with i, the leftmost element that changed */
+                    /* yield tuple(pool[k] for k in indices[:r]) */
+                    index = indices[k];
+                    elem = PyTuple_GET_ITEM(pool, index);
+                    Py_INCREF(elem);
+                    oldelem = PyTuple_GET_ITEM(result, k);
+                    PyTuple_SET_ITEM(result, k, elem);
+                    Py_DECREF(oldelem);
+                }
+                break;
+            }
+        }
+        /* If i is negative, then the cycles have all
+           rolled-over and we're done. */
+        if (i < 0)
+            goto empty;
+    }
+    Py_INCREF(result);
+    return result;
+
+empty:
+    po->stopped = 1;
+    return NULL;
+}
+
+PyDoc_STRVAR(permutations_doc,
+"permutations(iterable[, r]) --> permutations object\n\
+\n\
+Return successive r-length permutations of elements in the iterable.\n\n\
+permutations(range(3), 2) --> (0,1), (0,2), (1,0), (1,2), (2,0), (2,1)");
+
+static PyTypeObject permutations_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.permutations",                   /* tp_name */
+    sizeof(permutationsobject),         /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)permutations_dealloc,           /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    permutations_doc,                           /* tp_doc */
+    (traverseproc)permutations_traverse,        /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)permutations_next,            /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    permutations_new,                           /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* compress object ************************************************************/
+
+/* Equivalent to:
+
+    def compress(data, selectors):
+        "compress('ABCDEF', [1,0,1,0,1,1]) --> A C E F"
+        return (d for d, s in izip(data, selectors) if s)
+*/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *data;
+    PyObject *selectors;
+} compressobject;
+
+static PyTypeObject compress_type;
+
+static PyObject *
+compress_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    PyObject *seq1, *seq2;
+    PyObject *data=NULL, *selectors=NULL;
+    compressobject *lz;
+    static char *kwargs[] = {"data", "selectors", NULL};
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "OO:compress", kwargs, &seq1, &seq2))
+        return NULL;
+
+    data = PyObject_GetIter(seq1);
+    if (data == NULL)
+        goto fail;
+    selectors = PyObject_GetIter(seq2);
+    if (selectors == NULL)
+        goto fail;
+
+    /* create compressobject structure */
+    lz = (compressobject *)type->tp_alloc(type, 0);
+    if (lz == NULL)
+        goto fail;
+    lz->data = data;
+    lz->selectors = selectors;
+    return (PyObject *)lz;
+
+fail:
+    Py_XDECREF(data);
+    Py_XDECREF(selectors);
+    return NULL;
+}
+
+static void
+compress_dealloc(compressobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->data);
+    Py_XDECREF(lz->selectors);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+compress_traverse(compressobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->data);
+    Py_VISIT(lz->selectors);
+    return 0;
+}
+
+static PyObject *
+compress_next(compressobject *lz)
+{
+    PyObject *data = lz->data, *selectors = lz->selectors;
+    PyObject *datum, *selector;
+    PyObject *(*datanext)(PyObject *) = *Py_TYPE(data)->tp_iternext;
+    PyObject *(*selectornext)(PyObject *) = *Py_TYPE(selectors)->tp_iternext;
+    int ok;
+
+    while (1) {
+        /* Steps:  get datum, get selector, evaluate selector.
+           Order is important (to match the pure python version
+           in terms of which input gets a chance to raise an
+           exception first).
+        */
+
+        datum = datanext(data);
+        if (datum == NULL)
+            return NULL;
+
+        selector = selectornext(selectors);
+        if (selector == NULL) {
+            Py_DECREF(datum);
+            return NULL;
+        }
+
+        ok = PyObject_IsTrue(selector);
+        Py_DECREF(selector);
+        if (ok == 1)
+            return datum;
+        Py_DECREF(datum);
+        if (ok == -1)
+            return NULL;
+    }
+}
+
+PyDoc_STRVAR(compress_doc,
+"compress(data, selectors) --> iterator over selected data\n\
+\n\
+Return data elements corresponding to true selector elements.\n\
+Forms a shorter iterator from selected data elements using the\n\
+selectors to choose the data elements.");
+
+static PyTypeObject compress_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.compress",               /* tp_name */
+    sizeof(compressobject),             /* tp_basicsize */
+    0,                                                          /* tp_itemsize */
+    /* methods */
+    (destructor)compress_dealloc,       /* tp_dealloc */
+    0,                                                                  /* tp_print */
+    0,                                                                  /* tp_getattr */
+    0,                                                                  /* tp_setattr */
+    0,                                                                  /* tp_compare */
+    0,                                                                  /* tp_repr */
+    0,                                                                  /* tp_as_number */
+    0,                                                                  /* tp_as_sequence */
+    0,                                                                  /* tp_as_mapping */
+    0,                                                                  /* tp_hash */
+    0,                                                                  /* tp_call */
+    0,                                                                  /* tp_str */
+    PyObject_GenericGetAttr,                    /* tp_getattro */
+    0,                                                                  /* tp_setattro */
+    0,                                                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,                    /* tp_flags */
+    compress_doc,                                       /* tp_doc */
+    (traverseproc)compress_traverse,            /* tp_traverse */
+    0,                                                                  /* tp_clear */
+    0,                                                                  /* tp_richcompare */
+    0,                                                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                                  /* tp_iter */
+    (iternextfunc)compress_next,        /* tp_iternext */
+    0,                                                                  /* tp_methods */
+    0,                                                                  /* tp_members */
+    0,                                                                  /* tp_getset */
+    0,                                                                  /* tp_base */
+    0,                                                                  /* tp_dict */
+    0,                                                                  /* tp_descr_get */
+    0,                                                                  /* tp_descr_set */
+    0,                                                                  /* tp_dictoffset */
+    0,                                                                  /* tp_init */
+    0,                                                                  /* tp_alloc */
+    compress_new,                                       /* tp_new */
+    PyObject_GC_Del,                                    /* tp_free */
+};
+
+
+/* ifilter object ************************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *func;
+    PyObject *it;
+} ifilterobject;
+
+static PyTypeObject ifilter_type;
+
+static PyObject *
+ifilter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    PyObject *func, *seq;
+    PyObject *it;
+    ifilterobject *lz;
+
+    if (type == &ifilter_type && !_PyArg_NoKeywords("ifilter()", kwds))
+        return NULL;
+
+    if (!PyArg_UnpackTuple(args, "ifilter", 2, 2, &func, &seq))
+        return NULL;
+
+    /* Get iterator. */
+    it = PyObject_GetIter(seq);
+    if (it == NULL)
+        return NULL;
+
+    /* create ifilterobject structure */
+    lz = (ifilterobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_DECREF(it);
+        return NULL;
+    }
+    Py_INCREF(func);
+    lz->func = func;
+    lz->it = it;
+
+    return (PyObject *)lz;
+}
+
+static void
+ifilter_dealloc(ifilterobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->func);
+    Py_XDECREF(lz->it);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+ifilter_traverse(ifilterobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->it);
+    Py_VISIT(lz->func);
+    return 0;
+}
+
+static PyObject *
+ifilter_next(ifilterobject *lz)
+{
+    PyObject *item;
+    PyObject *it = lz->it;
+    long ok;
+    PyObject *(*iternext)(PyObject *);
+
+    iternext = *Py_TYPE(it)->tp_iternext;
+    for (;;) {
+        item = iternext(it);
+        if (item == NULL)
+            return NULL;
+
+        if (lz->func == Py_None || lz->func == (PyObject *)&PyBool_Type) {
+            ok = PyObject_IsTrue(item);
+        } else {
+            PyObject *good;
+            good = PyObject_CallFunctionObjArgs(lz->func,
+                                                item, NULL);
+            if (good == NULL) {
+                Py_DECREF(item);
+                return NULL;
+            }
+            ok = PyObject_IsTrue(good);
+            Py_DECREF(good);
+        }
+        if (ok)
+            return item;
+        Py_DECREF(item);
+    }
+}
+
+PyDoc_STRVAR(ifilter_doc,
+"ifilter(function or None, sequence) --> ifilter object\n\
+\n\
+Return those items of sequence for which function(item) is true.\n\
+If function is None, return the items that are true.");
+
+static PyTypeObject ifilter_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.ifilter",                /* tp_name */
+    sizeof(ifilterobject),              /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)ifilter_dealloc,        /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    ifilter_doc,                        /* tp_doc */
+    (traverseproc)ifilter_traverse,     /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)ifilter_next,         /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    ifilter_new,                        /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* ifilterfalse object ************************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *func;
+    PyObject *it;
+} ifilterfalseobject;
+
+static PyTypeObject ifilterfalse_type;
+
+static PyObject *
+ifilterfalse_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    PyObject *func, *seq;
+    PyObject *it;
+    ifilterfalseobject *lz;
+
+    if (type == &ifilterfalse_type &&
+        !_PyArg_NoKeywords("ifilterfalse()", kwds))
+        return NULL;
+
+    if (!PyArg_UnpackTuple(args, "ifilterfalse", 2, 2, &func, &seq))
+        return NULL;
+
+    /* Get iterator. */
+    it = PyObject_GetIter(seq);
+    if (it == NULL)
+        return NULL;
+
+    /* create ifilterfalseobject structure */
+    lz = (ifilterfalseobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_DECREF(it);
+        return NULL;
+    }
+    Py_INCREF(func);
+    lz->func = func;
+    lz->it = it;
+
+    return (PyObject *)lz;
+}
+
+static void
+ifilterfalse_dealloc(ifilterfalseobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->func);
+    Py_XDECREF(lz->it);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+ifilterfalse_traverse(ifilterfalseobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->it);
+    Py_VISIT(lz->func);
+    return 0;
+}
+
+static PyObject *
+ifilterfalse_next(ifilterfalseobject *lz)
+{
+    PyObject *item;
+    PyObject *it = lz->it;
+    long ok;
+    PyObject *(*iternext)(PyObject *);
+
+    iternext = *Py_TYPE(it)->tp_iternext;
+    for (;;) {
+        item = iternext(it);
+        if (item == NULL)
+            return NULL;
+
+        if (lz->func == Py_None || lz->func == (PyObject *)&PyBool_Type) {
+            ok = PyObject_IsTrue(item);
+        } else {
+            PyObject *good;
+            good = PyObject_CallFunctionObjArgs(lz->func,
+                                                item, NULL);
+            if (good == NULL) {
+                Py_DECREF(item);
+                return NULL;
+            }
+            ok = PyObject_IsTrue(good);
+            Py_DECREF(good);
+        }
+        if (!ok)
+            return item;
+        Py_DECREF(item);
+    }
+}
+
+PyDoc_STRVAR(ifilterfalse_doc,
+"ifilterfalse(function or None, sequence) --> ifilterfalse object\n\
+\n\
+Return those items of sequence for which function(item) is false.\n\
+If function is None, return the items that are false.");
+
+static PyTypeObject ifilterfalse_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.ifilterfalse",           /* tp_name */
+    sizeof(ifilterfalseobject),         /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)ifilterfalse_dealloc,           /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    ifilterfalse_doc,                   /* tp_doc */
+    (traverseproc)ifilterfalse_traverse,        /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)ifilterfalse_next,            /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    ifilterfalse_new,                   /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* count object ************************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    Py_ssize_t cnt;
+    PyObject *long_cnt;
+    PyObject *long_step;
+} countobject;
+
+/* Counting logic and invariants:
+
+fast_mode:  when cnt an integer < PY_SSIZE_T_MAX and no step is specified.
+
+    assert(cnt != PY_SSIZE_T_MAX && long_cnt == NULL && long_step==PyInt(1));
+    Advances with:  cnt += 1
+    When count hits Y_SSIZE_T_MAX, switch to slow_mode.
+
+slow_mode:  when cnt == PY_SSIZE_T_MAX, step is not int(1), or cnt is a float.
+
+    assert(cnt == PY_SSIZE_T_MAX && long_cnt != NULL && long_step != NULL);
+    All counting is done with python objects (no overflows or underflows).
+    Advances with:  long_cnt += long_step
+    Step may be zero -- effectively a slow version of repeat(cnt).
+    Either long_cnt or long_step may be a float, Fraction, or Decimal.
+*/
+
+static PyTypeObject count_type;
+
+static PyObject *
+count_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    countobject *lz;
+    int slow_mode = 0;
+    Py_ssize_t cnt = 0;
+    PyObject *long_cnt = NULL;
+    PyObject *long_step = NULL;
+    static char *kwlist[] = {"start", "step", 0};
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|OO:count",
+                    kwlist, &long_cnt, &long_step))
+        return NULL;
+
+    if ((long_cnt != NULL && !PyNumber_Check(long_cnt)) ||
+        (long_step != NULL && !PyNumber_Check(long_step))) {
+                    PyErr_SetString(PyExc_TypeError, "a number is required");
+                    return NULL;
+    }
+
+    if (long_cnt != NULL) {
+        cnt = PyInt_AsSsize_t(long_cnt);
+        if ((cnt == -1 && PyErr_Occurred()) || !PyInt_Check(long_cnt)) {
+            PyErr_Clear();
+            slow_mode = 1;
+        }
+        Py_INCREF(long_cnt);
+    } else {
+        cnt = 0;
+        long_cnt = PyInt_FromLong(0);
+    }
+
+    /* If not specified, step defaults to 1 */
+    if (long_step == NULL) {
+        long_step = PyInt_FromLong(1);
+        if (long_step == NULL) {
+            Py_DECREF(long_cnt);
+            return NULL;
+        }
+    } else
+        Py_INCREF(long_step);
+
+    assert(long_cnt != NULL && long_step != NULL);
+
+    /* Fast mode only works when the step is 1 */
+    if (!PyInt_Check(long_step) ||
+        PyInt_AS_LONG(long_step) != 1) {
+            slow_mode = 1;
+    }
+
+    if (slow_mode)
+        cnt = PY_SSIZE_T_MAX;
+    else
+        Py_CLEAR(long_cnt);
+
+    assert((cnt != PY_SSIZE_T_MAX && long_cnt == NULL && !slow_mode) ||
+           (cnt == PY_SSIZE_T_MAX && long_cnt != NULL && slow_mode));
+    assert(slow_mode ||
+           (PyInt_Check(long_step) && PyInt_AS_LONG(long_step) == 1));
+
+    /* create countobject structure */
+    lz = (countobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_XDECREF(long_cnt);
+        return NULL;
+    }
+    lz->cnt = cnt;
+    lz->long_cnt = long_cnt;
+    lz->long_step = long_step;
+
+    return (PyObject *)lz;
+}
+
+static void
+count_dealloc(countobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->long_cnt);
+    Py_XDECREF(lz->long_step);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+count_traverse(countobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->long_cnt);
+    Py_VISIT(lz->long_step);
+    return 0;
+}
+
+static PyObject *
+count_nextlong(countobject *lz)
+{
+    PyObject *long_cnt;
+    PyObject *stepped_up;
+
+    long_cnt = lz->long_cnt;
+    if (long_cnt == NULL) {
+        /* Switch to slow_mode */
+        long_cnt = PyInt_FromSsize_t(PY_SSIZE_T_MAX);
+        if (long_cnt == NULL)
+            return NULL;
+    }
+    assert(lz->cnt == PY_SSIZE_T_MAX && long_cnt != NULL);
+
+    stepped_up = PyNumber_Add(long_cnt, lz->long_step);
+    if (stepped_up == NULL)
+        return NULL;
+    lz->long_cnt = stepped_up;
+    return long_cnt;
+}
+
+static PyObject *
+count_next(countobject *lz)
+{
+    if (lz->cnt == PY_SSIZE_T_MAX)
+        return count_nextlong(lz);
+    return PyInt_FromSsize_t(lz->cnt++);
+}
+
+static PyObject *
+count_repr(countobject *lz)
+{
+    PyObject *cnt_repr, *step_repr = NULL;
+    PyObject *result = NULL;
+
+    if (lz->cnt != PY_SSIZE_T_MAX)
+                return PyString_FromFormat("count(%zd)", lz->cnt);
+
+    cnt_repr = PyObject_Repr(lz->long_cnt);
+    if (cnt_repr == NULL)
+        return NULL;
+
+    if (PyInt_Check(lz->long_step) && PyInt_AS_LONG(lz->long_step) == 1) {
+                    /* Don't display step when it is an integer equal to 1 */
+            result = PyString_FromFormat("count(%s)",
+                                                                     PyString_AS_STRING(cnt_repr));
+    } else {
+        step_repr = PyObject_Repr(lz->long_step);
+        if (step_repr != NULL)
+            result = PyString_FromFormat("count(%s, %s)",
+                                                                    PyString_AS_STRING(cnt_repr),
+                                                                    PyString_AS_STRING(step_repr));
+    }
+    Py_DECREF(cnt_repr);
+    Py_XDECREF(step_repr);
+    return result;
+}
+
+static PyObject *
+count_reduce(countobject *lz)
+{
+    if (lz->cnt == PY_SSIZE_T_MAX)
+        return Py_BuildValue("O(OO)", Py_TYPE(lz), lz->long_cnt, lz->long_step);
+    return Py_BuildValue("O(n)", Py_TYPE(lz), lz->cnt);
+}
+
+PyDoc_STRVAR(count_reduce_doc, "Return state information for pickling.");
+
+static PyMethodDef count_methods[] = {
+    {"__reduce__",      (PyCFunction)count_reduce,      METH_NOARGS,
+     count_reduce_doc},
+    {NULL,              NULL}   /* sentinel */
+};
+
+PyDoc_STRVAR(count_doc,
+                         "count(start=0, step=1) --> count object\n\
+\n\
+Return a count object whose .next() method returns consecutive values.\n\
+Equivalent to:\n\n\
+    def count(firstval=0, step=1):\n\
+    x = firstval\n\
+    while 1:\n\
+        yield x\n\
+        x += step\n");
+
+static PyTypeObject count_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.count",                  /* tp_name */
+    sizeof(countobject),                /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)count_dealloc,          /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    (reprfunc)count_repr,               /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,                    /* tp_flags */
+    count_doc,                          /* tp_doc */
+    (traverseproc)count_traverse,                               /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)count_next,           /* tp_iternext */
+    count_methods,                              /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    count_new,                          /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* izip object ************************************************************/
+
+#include "Python.h"
+
+typedef struct {
+    PyObject_HEAD
+    Py_ssize_t          tuplesize;
+    PyObject *ittuple;                  /* tuple of iterators */
+    PyObject *result;
+} izipobject;
+
+static PyTypeObject izip_type;
+
+static PyObject *
+izip_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    izipobject *lz;
+    Py_ssize_t i;
+    PyObject *ittuple;  /* tuple of iterators */
+    PyObject *result;
+    Py_ssize_t tuplesize = PySequence_Length(args);
+
+    if (type == &izip_type && !_PyArg_NoKeywords("izip()", kwds))
+        return NULL;
+
+    /* args must be a tuple */
+    assert(PyTuple_Check(args));
+
+    /* obtain iterators */
+    ittuple = PyTuple_New(tuplesize);
+    if (ittuple == NULL)
+        return NULL;
+    for (i=0; i < tuplesize; ++i) {
+        PyObject *item = PyTuple_GET_ITEM(args, i);
+        PyObject *it = PyObject_GetIter(item);
+        if (it == NULL) {
+            if (PyErr_ExceptionMatches(PyExc_TypeError))
+                PyErr_Format(PyExc_TypeError,
+                    "izip argument #%zd must support iteration",
+                    i+1);
+            Py_DECREF(ittuple);
+            return NULL;
+        }
+        PyTuple_SET_ITEM(ittuple, i, it);
+    }
+
+    /* create a result holder */
+    result = PyTuple_New(tuplesize);
+    if (result == NULL) {
+        Py_DECREF(ittuple);
+        return NULL;
+    }
+    for (i=0 ; i < tuplesize ; i++) {
+        Py_INCREF(Py_None);
+        PyTuple_SET_ITEM(result, i, Py_None);
+    }
+
+    /* create izipobject structure */
+    lz = (izipobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_DECREF(ittuple);
+        Py_DECREF(result);
+        return NULL;
+    }
+    lz->ittuple = ittuple;
+    lz->tuplesize = tuplesize;
+    lz->result = result;
+
+    return (PyObject *)lz;
+}
+
+static void
+izip_dealloc(izipobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->ittuple);
+    Py_XDECREF(lz->result);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+izip_traverse(izipobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->ittuple);
+    Py_VISIT(lz->result);
+    return 0;
+}
+
+static PyObject *
+izip_next(izipobject *lz)
+{
+    Py_ssize_t i;
+    Py_ssize_t tuplesize = lz->tuplesize;
+    PyObject *result = lz->result;
+    PyObject *it;
+    PyObject *item;
+    PyObject *olditem;
+
+    if (tuplesize == 0)
+        return NULL;
+    if (Py_REFCNT(result) == 1) {
+        Py_INCREF(result);
+        for (i=0 ; i < tuplesize ; i++) {
+            it = PyTuple_GET_ITEM(lz->ittuple, i);
+            item = (*Py_TYPE(it)->tp_iternext)(it);
+            if (item == NULL) {
+                Py_DECREF(result);
+                return NULL;
+            }
+            olditem = PyTuple_GET_ITEM(result, i);
+            PyTuple_SET_ITEM(result, i, item);
+            Py_DECREF(olditem);
+        }
+    } else {
+        result = PyTuple_New(tuplesize);
+        if (result == NULL)
+            return NULL;
+        for (i=0 ; i < tuplesize ; i++) {
+            it = PyTuple_GET_ITEM(lz->ittuple, i);
+            item = (*Py_TYPE(it)->tp_iternext)(it);
+            if (item == NULL) {
+                Py_DECREF(result);
+                return NULL;
+            }
+            PyTuple_SET_ITEM(result, i, item);
+        }
+    }
+    return result;
+}
+
+PyDoc_STRVAR(izip_doc,
+"izip(iter1 [,iter2 [...]]) --> izip object\n\
+\n\
+Return a izip object whose .next() method returns a tuple where\n\
+the i-th element comes from the i-th iterable argument.  The .next()\n\
+method continues until the shortest iterable in the argument sequence\n\
+is exhausted and then it raises StopIteration.  Works like the zip()\n\
+function but consumes less memory by returning an iterator instead of\n\
+a list.");
+
+static PyTypeObject izip_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.izip",                   /* tp_name */
+    sizeof(izipobject),                 /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)izip_dealloc,           /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    izip_doc,                           /* tp_doc */
+    (traverseproc)izip_traverse,    /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)izip_next,            /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    izip_new,                           /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+
+/* repeat object ************************************************************/
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *element;
+    Py_ssize_t cnt;
+} repeatobject;
+
+static PyTypeObject repeat_type;
+
+static PyObject *
+repeat_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    repeatobject *ro;
+    PyObject *element;
+    Py_ssize_t cnt = -1;
+    static char *kwargs[] = {"object", "times", NULL};
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|n:repeat", kwargs,
+                                     &element, &cnt))
+        return NULL;
+
+    if (PyTuple_Size(args) == 2 && cnt < 0)
+        cnt = 0;
+
+    ro = (repeatobject *)type->tp_alloc(type, 0);
+    if (ro == NULL)
+        return NULL;
+    Py_INCREF(element);
+    ro->element = element;
+    ro->cnt = cnt;
+    return (PyObject *)ro;
+}
+
+static void
+repeat_dealloc(repeatobject *ro)
+{
+    PyObject_GC_UnTrack(ro);
+    Py_XDECREF(ro->element);
+    Py_TYPE(ro)->tp_free(ro);
+}
+
+static int
+repeat_traverse(repeatobject *ro, visitproc visit, void *arg)
+{
+    Py_VISIT(ro->element);
+    return 0;
+}
+
+static PyObject *
+repeat_next(repeatobject *ro)
+{
+    if (ro->cnt == 0)
+        return NULL;
+    if (ro->cnt > 0)
+        ro->cnt--;
+    Py_INCREF(ro->element);
+    return ro->element;
+}
+
+static PyObject *
+repeat_repr(repeatobject *ro)
+{
+    PyObject *result, *objrepr;
+
+    objrepr = PyObject_Repr(ro->element);
+    if (objrepr == NULL)
+        return NULL;
+
+    if (ro->cnt == -1)
+        result = PyString_FromFormat("repeat(%s)",
+            PyString_AS_STRING(objrepr));
+    else
+        result = PyString_FromFormat("repeat(%s, %zd)",
+            PyString_AS_STRING(objrepr), ro->cnt);
+    Py_DECREF(objrepr);
+    return result;
+}
+
+static PyObject *
+repeat_len(repeatobject *ro)
+{
+    if (ro->cnt == -1) {
+        PyErr_SetString(PyExc_TypeError, "len() of unsized object");
+        return NULL;
+    }
+    return PyInt_FromSize_t(ro->cnt);
+}
+
+PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
+
+static PyMethodDef repeat_methods[] = {
+    {"__length_hint__", (PyCFunction)repeat_len, METH_NOARGS, length_hint_doc},
+    {NULL,              NULL}           /* sentinel */
+};
+
+PyDoc_STRVAR(repeat_doc,
+"repeat(object [,times]) -> create an iterator which returns the object\n\
+for the specified number of times.  If not specified, returns the object\n\
+endlessly.");
+
+static PyTypeObject repeat_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.repeat",                 /* tp_name */
+    sizeof(repeatobject),               /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)repeat_dealloc,         /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    (reprfunc)repeat_repr,              /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    repeat_doc,                         /* tp_doc */
+    (traverseproc)repeat_traverse,      /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)repeat_next,          /* tp_iternext */
+    repeat_methods,                     /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    repeat_new,                         /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+/* iziplongest object ************************************************************/
+
+#include "Python.h"
+
+typedef struct {
+    PyObject_HEAD
+    Py_ssize_t tuplesize;
+    Py_ssize_t numactive;
+    PyObject *ittuple;                  /* tuple of iterators */
+    PyObject *result;
+    PyObject *fillvalue;
+} iziplongestobject;
+
+static PyTypeObject iziplongest_type;
+
+static PyObject *
+izip_longest_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    iziplongestobject *lz;
+    Py_ssize_t i;
+    PyObject *ittuple;  /* tuple of iterators */
+    PyObject *result;
+    PyObject *fillvalue = Py_None;
+    Py_ssize_t tuplesize = PySequence_Length(args);
+
+    if (kwds != NULL && PyDict_CheckExact(kwds) && PyDict_Size(kwds) > 0) {
+        fillvalue = PyDict_GetItemString(kwds, "fillvalue");
+        if (fillvalue == NULL  ||  PyDict_Size(kwds) > 1) {
+            PyErr_SetString(PyExc_TypeError,
+                "izip_longest() got an unexpected keyword argument");
+            return NULL;
+        }
+    }
+
+    /* args must be a tuple */
+    assert(PyTuple_Check(args));
+
+    /* obtain iterators */
+    ittuple = PyTuple_New(tuplesize);
+    if (ittuple == NULL)
+        return NULL;
+    for (i=0; i < tuplesize; ++i) {
+        PyObject *item = PyTuple_GET_ITEM(args, i);
+        PyObject *it = PyObject_GetIter(item);
+        if (it == NULL) {
+            if (PyErr_ExceptionMatches(PyExc_TypeError))
+                PyErr_Format(PyExc_TypeError,
+                    "izip_longest argument #%zd must support iteration",
+                    i+1);
+            Py_DECREF(ittuple);
+            return NULL;
+        }
+        PyTuple_SET_ITEM(ittuple, i, it);
+    }
+
+    /* create a result holder */
+    result = PyTuple_New(tuplesize);
+    if (result == NULL) {
+        Py_DECREF(ittuple);
+        return NULL;
+    }
+    for (i=0 ; i < tuplesize ; i++) {
+        Py_INCREF(Py_None);
+        PyTuple_SET_ITEM(result, i, Py_None);
+    }
+
+    /* create iziplongestobject structure */
+    lz = (iziplongestobject *)type->tp_alloc(type, 0);
+    if (lz == NULL) {
+        Py_DECREF(ittuple);
+        Py_DECREF(result);
+        return NULL;
+    }
+    lz->ittuple = ittuple;
+    lz->tuplesize = tuplesize;
+    lz->numactive = tuplesize;
+    lz->result = result;
+    Py_INCREF(fillvalue);
+    lz->fillvalue = fillvalue;
+    return (PyObject *)lz;
+}
+
+static void
+izip_longest_dealloc(iziplongestobject *lz)
+{
+    PyObject_GC_UnTrack(lz);
+    Py_XDECREF(lz->ittuple);
+    Py_XDECREF(lz->result);
+    Py_XDECREF(lz->fillvalue);
+    Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+izip_longest_traverse(iziplongestobject *lz, visitproc visit, void *arg)
+{
+    Py_VISIT(lz->ittuple);
+    Py_VISIT(lz->result);
+    Py_VISIT(lz->fillvalue);
+    return 0;
+}
+
+static PyObject *
+izip_longest_next(iziplongestobject *lz)
+{
+    Py_ssize_t i;
+    Py_ssize_t tuplesize = lz->tuplesize;
+    PyObject *result = lz->result;
+    PyObject *it;
+    PyObject *item;
+    PyObject *olditem;
+
+    if (tuplesize == 0)
+        return NULL;
+    if (lz->numactive == 0)
+        return NULL;
+    if (Py_REFCNT(result) == 1) {
+        Py_INCREF(result);
+        for (i=0 ; i < tuplesize ; i++) {
+            it = PyTuple_GET_ITEM(lz->ittuple, i);
+            if (it == NULL) {
+                Py_INCREF(lz->fillvalue);
+                item = lz->fillvalue;
+            } else {
+                item = PyIter_Next(it);
+                if (item == NULL) {
+                    lz->numactive -= 1;
+                    if (lz->numactive == 0 || PyErr_Occurred()) {
+                        lz->numactive = 0;
+                        Py_DECREF(result);
+                        return NULL;
+                    } else {
+                        Py_INCREF(lz->fillvalue);
+                        item = lz->fillvalue;
+                        PyTuple_SET_ITEM(lz->ittuple, i, NULL);
+                        Py_DECREF(it);
+                    }
+                }
+            }
+            olditem = PyTuple_GET_ITEM(result, i);
+            PyTuple_SET_ITEM(result, i, item);
+            Py_DECREF(olditem);
+        }
+    } else {
+        result = PyTuple_New(tuplesize);
+        if (result == NULL)
+            return NULL;
+        for (i=0 ; i < tuplesize ; i++) {
+            it = PyTuple_GET_ITEM(lz->ittuple, i);
+            if (it == NULL) {
+                Py_INCREF(lz->fillvalue);
+                item = lz->fillvalue;
+            } else {
+                item = PyIter_Next(it);
+                if (item == NULL) {
+                    lz->numactive -= 1;
+                    if (lz->numactive == 0 || PyErr_Occurred()) {
+                        lz->numactive = 0;
+                        Py_DECREF(result);
+                        return NULL;
+                    } else {
+                        Py_INCREF(lz->fillvalue);
+                        item = lz->fillvalue;
+                        PyTuple_SET_ITEM(lz->ittuple, i, NULL);
+                        Py_DECREF(it);
+                    }
+                }
+            }
+            PyTuple_SET_ITEM(result, i, item);
+        }
+    }
+    return result;
+}
+
+PyDoc_STRVAR(izip_longest_doc,
+"izip_longest(iter1 [,iter2 [...]], [fillvalue=None]) --> izip_longest object\n\
+\n\
+Return an izip_longest object whose .next() method returns a tuple where\n\
+the i-th element comes from the i-th iterable argument.  The .next()\n\
+method continues until the longest iterable in the argument sequence\n\
+is exhausted and then it raises StopIteration.  When the shorter iterables\n\
+are exhausted, the fillvalue is substituted in their place.  The fillvalue\n\
+defaults to None or can be specified by a keyword argument.\n\
+");
+
+static PyTypeObject iziplongest_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "itertools.izip_longest",           /* tp_name */
+    sizeof(iziplongestobject),          /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    /* methods */
+    (destructor)izip_longest_dealloc,           /* tp_dealloc */
+    0,                                  /* tp_print */
+    0,                                  /* tp_getattr */
+    0,                                  /* tp_setattr */
+    0,                                  /* tp_compare */
+    0,                                  /* tp_repr */
+    0,                                  /* tp_as_number */
+    0,                                  /* tp_as_sequence */
+    0,                                  /* tp_as_mapping */
+    0,                                  /* tp_hash */
+    0,                                  /* tp_call */
+    0,                                  /* tp_str */
+    PyObject_GenericGetAttr,            /* tp_getattro */
+    0,                                  /* tp_setattro */
+    0,                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_BASETYPE,            /* tp_flags */
+    izip_longest_doc,                           /* tp_doc */
+    (traverseproc)izip_longest_traverse,    /* tp_traverse */
+    0,                                  /* tp_clear */
+    0,                                  /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    PyObject_SelfIter,                  /* tp_iter */
+    (iternextfunc)izip_longest_next,            /* tp_iternext */
+    0,                                  /* tp_methods */
+    0,                                  /* tp_members */
+    0,                                  /* tp_getset */
+    0,                                  /* tp_base */
+    0,                                  /* tp_dict */
+    0,                                  /* tp_descr_get */
+    0,                                  /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    0,                                  /* tp_init */
+    0,                                  /* tp_alloc */
+    izip_longest_new,                           /* tp_new */
+    PyObject_GC_Del,                    /* tp_free */
+};
+
+/* module level code ********************************************************/
+
+PyDoc_STRVAR(module_doc,
+"Functional tools for creating and using iterators.\n\
+\n\
+Infinite iterators:\n\
+count([n]) --> n, n+1, n+2, ...\n\
+cycle(p) --> p0, p1, ... plast, p0, p1, ...\n\
+repeat(elem [,n]) --> elem, elem, elem, ... endlessly or up to n times\n\
+\n\
+Iterators terminating on the shortest input sequence:\n\
+chain(p, q, ...) --> p0, p1, ... plast, q0, q1, ... \n\
+compress(data, selectors) --> (d[0] if s[0]), (d[1] if s[1]), ...\n\
+dropwhile(pred, seq) --> seq[n], seq[n+1], starting when pred fails\n\
+groupby(iterable[, keyfunc]) --> sub-iterators grouped by value of keyfunc(v)\n\
+ifilter(pred, seq) --> elements of seq where pred(elem) is True\n\
+ifilterfalse(pred, seq) --> elements of seq where pred(elem) is False\n\
+islice(seq, [start,] stop [, step]) --> elements from\n\
+       seq[start:stop:step]\n\
+imap(fun, p, q, ...) --> fun(p0, q0), fun(p1, q1), ...\n\
+starmap(fun, seq) --> fun(*seq[0]), fun(*seq[1]), ...\n\
+tee(it, n=2) --> (it1, it2 , ... itn) splits one iterator into n\n\
+takewhile(pred, seq) --> seq[0], seq[1], until pred fails\n\
+izip(p, q, ...) --> (p[0], q[0]), (p[1], q[1]), ... \n\
+izip_longest(p, q, ...) --> (p[0], q[0]), (p[1], q[1]), ... \n\
+\n\
+Combinatoric generators:\n\
+product(p, q, ... [repeat=1]) --> cartesian product\n\
+permutations(p[, r])\n\
+combinations(p, r)\n\
+combinations_with_replacement(p, r)\n\
+");
+
+
+static PyMethodDef module_methods[] = {
+    {"tee",     (PyCFunction)tee,       METH_VARARGS, tee_doc},
+    {NULL,              NULL}           /* sentinel */
+};
+
+PyMODINIT_FUNC
+inititertools(void)
+{
+    int i;
+    PyObject *m;
+    char *name;
+    PyTypeObject *typelist[] = {
+        &combinations_type,
+        &cwr_type,
+        &cycle_type,
+        &dropwhile_type,
+        &takewhile_type,
+        &islice_type,
+        &starmap_type,
+        &imap_type,
+        &chain_type,
+        &compress_type,
+        &ifilter_type,
+        &ifilterfalse_type,
+        &count_type,
+        &izip_type,
+        &iziplongest_type,
+        &permutations_type,
+        &product_type,
+        &repeat_type,
+        &groupby_type,
+        NULL
+    };
+
+    Py_TYPE(&teedataobject_type) = &PyType_Type;
+    m = Py_InitModule3("itertools", module_methods, module_doc);
+    if (m == NULL)
+        return;
+
+    for (i=0 ; typelist[i] != NULL ; i++) {
+        if (PyType_Ready(typelist[i]) < 0)
+            return;
+        name = strchr(typelist[i]->tp_name, '.');
+        assert (name != NULL);
+        Py_INCREF(typelist[i]);
+        PyModule_AddObject(m, name+1, (PyObject *)typelist[i]);
+    }
+
+    if (PyType_Ready(&teedataobject_type) < 0)
+        return;
+    if (PyType_Ready(&tee_type) < 0)
+        return;
+    if (PyType_Ready(&_grouper_type) < 0)
+        return;
+}
-- 
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