When inheriting from a type that defines an __eq__ operation, that __eq__ will override the built-in __eq__. In the case of the MutableMapping type, that means that it will try to use element-wise comparison against any other mapping type. This is effectively an attractive nuisance. Instead, we explicitly use the default comparison, which is based on object identity rather than contents or anything.
When inheriting from a type that defines an
__eq__operation, that__eq__will override the built-in__eq__. In the case of theMutableMappingtype, that means that it will try to use element-wise comparison against any other mapping type. This is effectively an attractive nuisance. Instead, we explicitly use the default comparison, which is based on object identity rather than contents or anything.