class M(object): is a new-style class in Python 2.x, in which it's the correct syntax: https://docs.python.org/2/glossary.html#term-new-style-class https://doc

class M(object): is a new-style class in Python 2.x, in which it's the correct syntax: https://docs.python.org/2/glossary.html#term-new-style-class https://docs.python.org/2/glossary.html#term-new-style-class It's different in Python 3 but that doesn't matter because Python 3 is largely irrelevant.