Method _persistent_id

Lib/test/test_pickle.py:305–308

(subself, obj)

            def persistent_id(subself, obj):
                raise AssertionError('should never be called')
            def _persistent_id(subself, obj):
                called.append(obj)
                self.assertIsNone(super().persistent_id(obj))
                return obj

        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
            f = io.BytesIO()