関連ワード:  why we use __main__ in python    why we use __ name __ == '__ main __' in python    why we use main function in python    why do we use main in python    why we use if __ name __ == '__ main __' in python    why do we use def main in python    why do we use if __ name __ == '__ main __' in python    what does __main__ mean in python    what does __main__ do in python