def test_instance(self):
        """
        Test references search through an object attribute.
        """
        class Dummy:
            pass
        o = object()
        d = Dummy()
        d.o = o

        self.assertIn(".o", reflect.objgrep(d, o, reflect.isSame))

        Test references search through an object attribute.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_reflect.py