def test_effect_of_strategy(self):
        self.responses_test([C, C], [C, C], [D])
        self.responses_test([C, C, D, D], [C, C, C, D], [C])
Comparisons to singletons like None should always be done
dataset/ETHPy150Open Axelrod-Python/Axelrod/axelrod/tests/unit/test_titfortat.py/TestSneakyTitForTat.test_effect_of_strategy--crossover with--dataset/ETHPy150Open kivy/plyer/plyer/tools/pep8checker/pep8.py/comparison_to_singleton