class Payment:

      def pay(self,money):

            raise Notlmplemented

class Wechat(Payment):

    def pay(self, money):

        print('已经用微信支付了%s元' % money)

class Alipay(Payment):

    def pay(self, money):

        print('已经用支付宝支付了%s元' % money)

class Applepay(Payment):

    def fuqian(self, money):

        print('已经用applepay支付了%s元' % money)

def pay(pay_obj, money):  # 统一支付入口

    pay_obj.pay(money)   

wechat = Wechat()

ali = Alipay()

app = Applepay()

pay(ali,200)

pay(app,200)

app = Applepay()

TypeError: Can't instantiate abstract class Applepay with abstract methods pay

from abc import abstractmethod, ABCMeta

class Payment(metaclass=ABCMeta):  # 元类 默认的元类 type

    @abstractmethod

    def pay(self, money): pass  # 没有实现这个方法

import abc

class Animal(metaclass=abc.ABCMeta): #同一类事物:动物

    @abc.abstractmethod

    def talk(self):

        pass

class People(Animal): #动物的形态之一:人

    def talk(self):

        print('say hello')

class Dog(Animal): #动物的形态之二:狗

    def talk(self):

        print('say wangwang')

class Pig(Animal): #动物的形态之三:猪

    def talk(self):

        print('say aoao')