def test_prefix(self):
        """
        If a prefix is given, L{prefixedMethods} returns only methods named
        with that prefix.
        """
        x = Separate()
        output = prefixedMethods(x, 'good_')
        self.assertEqual([x.good_method], output)

        If a prefix is given, L{prefixedMethods} returns only methods named
        with that prefix.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_reflect.py