def test_subCommandsType(self):
        """
        L{TwistOptions.subCommands} is an iterable of tuples as expected by
        L{twisted.python.usage.Options}.
        """
        options = TwistOptions()

        for name, shortcut, parser, doc in options.subCommands:
            self.assertIsInstance(name, str)
            self.assertIdentical(shortcut, None)
            self.assertTrue(callable(parser))
            self.assertIsInstance(doc, str)

        L{TwistOptions.subCommands} is an iterable of tuples as expected by
        L{twisted.python.usage.Options}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/application/twist/test/test_options.py