Add Counter() to __all__.
diff --git a/Lib/collections.py b/Lib/collections.py
index fe33a12..1d3fb40 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -1,4 +1,4 @@
-__all__ = ['deque', 'defaultdict', 'namedtuple']
+__all__ = ['Counter', 'deque', 'defaultdict', 'namedtuple']
 # For bootstrapping reasons, the collection ABCs are defined in _abcoll.py.
 # They should however be considered an integral part of collections.py.
 from _abcoll import *