抽象类

from abc import ABCMeta,abstractclassmethod

class A(metaclass=ABCMeta):
    def __init__(self):
        pass
    @abstractclassmethod
    def say(self,s):
        pass

class B(A):
    def __init__(self):
        pass
    def say(self,s):
        print(s)

b=B()
b.say("hello")

hello