Repaired grammar in new comment.
diff --git a/Lib/pickle.py b/Lib/pickle.py
index 47a61ae..4e75416 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -213,7 +213,7 @@
# The use of the Unpickler memo length as the memo key is just a
# convention. The only requirement is that the memo values be unique.
# But there appears no advantage to any other scheme, and this
- # scheme allows the Unpickler memo to implemented as a plain (but
+ # scheme allows the Unpickler memo to be implemented as a plain (but
# growable) array, indexed by memo key.
d = id(obj)
memo_len = len(self.memo)