抽象类和抽象方法

import abc
class Foo(metaclass=abc.ABCMeta):
    def f1(self):
        print(123)
    @abc.abstractmethod
    def f2(self):pass

class Bar(Foo):
    def f2(self): print(666)
obj = Bar()


"""
@abc.abstractmethod
TypeError: Can't instantiate abstract class Bar with abstract method f2
"""