def test_everything(self):
        """
        Test references search using complex set of objects.
        """
        class Dummy:
            def method(self):
                pass

        o = Dummy()
        D1 = {(): "baz", None: "Quux", o: "Foosh"}
        L = [None, (), D1, 3]
        T = (L, {}, Dummy())
        D2 = {0: "foo", 1: "bar", 2: T}
        i = Dummy()
        i.attr = D2
        m = i.method
        w = weakref.ref(m)

        self.assertIn("().__self__.attr[2][0][2]{'Foosh'}",
                      reflect.objgrep(w, o, reflect.isSame))

        Test references search using complex set of objects.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_reflect.py