Class SizeBlock

Lib/test/test_collections.py:1120–1123

        self.assertNotIsInstance(ColNoCont(), Collection)
        # Check None blocking
        class SizeBlock:
            def __iter__(self): return iter([])
            def __contains__(self): return False
            __len__ = None
        class IterBlock:
            def __len__(self): return 0
            def __contains__(self): return True