From 9e8dbbcdcd462efc8f50008c7182dd399de89097 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Sat, 14 Feb 2009 04:21:49 +0000
Subject: Add keyword argument support to itertools.count().

---
 Doc/library/itertools.rst  |  5 +++--
 Lib/test/test_itertools.py |  1 +
 Modules/itertoolsmodule.c  | 11 +++++------
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index fda3beb..ad5a23b 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -194,15 +194,16 @@ loops that truncate the stream.
    .. versionadded:: 3.1
 
 
-.. function:: count(n=0, step=1)
+.. function:: count(start=0, step=1)
 
    Make an iterator that returns evenly spaced values starting with *n*. Often
    used as an argument to :func:`map` to generate consecutive data points.
    Also, used with :func:`zip` to add sequence numbers.  Equivalent to::
 
-      def count(n=0, step=1):
+      def count(start=0, step=1):
           # count(10) --> 10 11 12 13 14 ...
           # count(2.5, 0.5) -> 3.5 3.0 4.5 ...
+          n = start
           while True:
               yield n
               n += step
diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
index 31ef2e1..812a1ef 100644
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -355,6 +355,7 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(lzip('abc',count(2,3)), [('a', 2), ('b', 5), ('c', 8)])
         self.assertEqual(lzip('abc',count(2,0)), [('a', 2), ('b', 2), ('c', 2)])
         self.assertEqual(lzip('abc',count(2,1)), [('a', 2), ('b', 3), ('c', 4)])
+        self.assertEqual(lzip('abc',count(2,3)), [('a', 2), ('b', 5), ('c', 8)])
         self.assertEqual(take(20, count(maxsize-15, 3)), take(20, range(maxsize-15, maxsize+100, 3)))
         self.assertEqual(take(20, count(-maxsize-15, 3)), take(20, range(-maxsize-15,-maxsize+100, 3)))
         self.assertEqual(take(3, count(2, 3.25-4j)), [2, 5.25-4j, 8.5-8j])
diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index 75c6e7e..a44d2ae 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -2916,11 +2916,10 @@ count_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 	Py_ssize_t cnt = 0;
 	PyObject *long_cnt = NULL;
 	PyObject *long_step = NULL;
+	static char *kwlist[] = {"start", "step", 0};
 
-	if (type == &count_type && !_PyArg_NoKeywords("count()", kwds))
-		return NULL;
-
-	if (!PyArg_UnpackTuple(args, "count", 0, 2, &long_cnt, &long_step))
+	if (!PyArg_ParseTupleAndKeywords(args, kwds, "|OO:count",
+			kwlist, &long_cnt, &long_step))
 		return NULL;
 
 	if (long_cnt != NULL && !PyNumber_Check(long_cnt) ||
@@ -3027,10 +3026,10 @@ count_repr(countobject *lz)
 }
 
 PyDoc_STRVAR(count_doc,
-			 "count([firstval[, step]]) --> count object\n\
+			 "count([start[, step]]) --> count object\n\
 \n\
 Return a count object whose .__next__() method returns consecutive\n\
-integers starting from zero or, if specified, from firstval.\n\
+integers starting from zero or, if specified, from start.\n\
 If step is specified, counts by that interval.  Equivalent to:\n\n\
     def count(firstval=0, step=1):\n\
         x = firstval\n\
-- 
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