No need to register classes that already inherit from ABCs.

Lib/UserList.py

@@ -71,5 +71,3 @@ class UserList(collections.MutableSequence):
             self.data.extend(other.data)
         else:
             self.data.extend(other)
-
-collections.MutableSequence.register(UserList)

Lib/UserString.py

@@ -235,8 +235,6 @@ class MutableString(UserString, collections.MutableSequence):
     def insert(self, index, value):
         self[index:index] = value
 
-collections.MutableSequence.register(MutableString)
-
 if __name__ == "__main__":
     # execute the regression test to stdout, if called as a script:
     import os

Lib/collections.py

@@ -160,8 +160,6 @@ class UserDict(MutableMapping):
             d[key] = value
         return d
 
-MutableMapping.register(UserDict)
-
 
 
 ################################################################################

Lib/weakref.py

@@ -194,7 +194,6 @@ class WeakValueDictionary(collections.MutableMapping):
                 L.append(o)
         return L
 
-collections.MutableMapping.register(WeakValueDictionary)
 
 class KeyedRef(ref):
     """Specialized reference that includes a key corresponding to the value.
@@ -350,5 +349,3 @@ class WeakKeyDictionary(collections.MutableMapping):
                 d[ref(key, self._remove)] = value
         if len(kwargs):
             self.update(kwargs)
-
-collections.MutableMapping.register(WeakKeyDictionary)