From 7832d4d534ff7105a0253694db734d5007b62e91 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Sat, 23 Feb 2008 10:04:15 +0000
Subject: [PATCH] Add recipe using itertools.product().

---
 Doc/library/itertools.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index 7d1ec966405..5cc3e08fa82 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -559,3 +559,9 @@ which incur interpreter overhead. ::
                pending -= 1
                nexts = cycle(islice(nexts, pending))
 
+   def powerset(iterable):
+       "powerset('ab') --> set([]), set(['b']), set(['a']), set(['a', 'b'])"
+       skip = object()
+       for t in product(*izip(repeat(skip), iterable)):
+           yield set(e for e in t if e is not skip)
+