def test_simple_probe_debug(self):
        pyrtl.set_debug_mode()
        i = pyrtl.Input(1)
        o = pyrtl.Output(1)
        output = six.StringIO()
        sys.stdout = output
        o <<= pyrtl.probe(i + 1, name="probe0")
        sys.stdout = sys.__stdout__
        self.assertTrue(output.getvalue().startswith("Probe: probe0"))
        pyrtl.set_debug_mode(False)