Method Y

Lib/test/test_inspect/test_inspect.py:2141–2145

(le)

        # The infamous Y combinator.
        def Y(le):
            def g(f):
                return le(lambda x: f(f)(x))
            Y.g_ref = g
            return g(g)

        def check_y_combinator(func):
            self.assertEqual(_nonlocal_vars(func), {'f': Y.g_ref})