typo in comment
diff --git a/Lib/UserDict.py b/Lib/UserDict.py
index f9ad471..fb9cdd5 100644
--- a/Lib/UserDict.py
+++ b/Lib/UserDict.py
@@ -77,7 +77,7 @@
# a minimum dictionary interface including getitem, setitem, delitem,
# and keys. Without knowledge of the subclass constructor, the mixin
# does not define __init__() or copy(). In addition to the four base
- # methods, progessively more efficiency comes with defining
+ # methods, progressively more efficiency comes with defining
# __contains__(), __iter__(), and iteritems().
# second level definitions support higher levels