Add recipe to docs.

Lib/test/test_itertools.py

@@ -1279,6 +1279,12 @@ Samuele
 ...     for n in xrange(2**len(pairs)):
 ...         yield set(x for m, x in pairs if m&n)
 
+>>> def compress(data, selectors):
+...     "compress('abcdef', [1,0,1,0,1,1]) --> a c e f"
+...     for d, s in izip(data, selectors):
+...         if s:
+...             yield d
+
 This is not part of the examples but it tests to make sure the definitions
 perform as purported.
 
@@ -1353,6 +1359,9 @@ False
 >>> map(sorted, powerset('ab'))
 [[], ['a'], ['b'], ['a', 'b']]
 
+>>> list(compress('abcdef', [1,0,1,0,1,1]))
+['a', 'c', 'e', 'f']
+
 """
 
 __test__ = {'libreftest' : libreftest}