assert theEmptyMapping is EmptyMapping()
assert theEmptySet is EmptySet()
assert theEmptySequence is EmptySequence()
assert theEmptyThree is EmptyThree()
if 1:
#tmp
assert not issubclass(EmptyMapping, Mapping)
#MappingView.register(EmptyMapping)
KeysView.register(EmptySet)
ItemsView.register(EmptySet)
ValuesView.register(EmptyCollection)
assert issubclass(EmptySet, KeysView)
assert issubclass(EmptySet, ItemsView)
assert issubclass(EmptySet, Set)
assert issubclass(EmptySet, MappingView)
assert issubclass(EmptyCollection, ValuesView)
assert issubclass(EmptyCollection, Collection)
assert issubclass(EmptyCollection, MappingView)
Mapping.register(EmptyMapping)
Set.register(EmptySet)
Sequence.register(EmptySequence)
def _abc_keysview_register(view_cls):
KeysView.register(view_cls)
