def test_mux_too_many_inputs_with_extra_kwarg(self):
        a = pyrtl.WireVector(name='a', bitwidth=3)
        b = pyrtl.WireVector(name='b', bitwidth=1)
        s = pyrtl.WireVector(name='s', bitwidth=2)
        with self.assertRaises(pyrtl.PyrtlError):
            r = pyrtl.corecircuits.mux(s, a, b, default=0, foo=1)