MappingView is Sized.

rhettinger · rhettinger · commit bfd061218b15 · 2008-02-09T10:04:32.000Z
diff --git a/Lib/_abcoll.py b/Lib/_abcoll.py
@@ -382,7 +382,7 @@ def __ne__(self, other):
         return not (self == other)
 
 
-class MappingView(metaclass=ABCMeta):
+class MappingView(Sized):
 
     def __init__(self, mapping):
         self._mapping = mapping
