class Operate:    def __init__(self):        passclass Add(Operate):    def result(self):        return (self.a+self.b)class Subduct(Operate):    def result(self):        return self.a-self.b        class Multiply(Operate):    def result(self):        return self.a*self.bclass Divide(Operate):    def result(self):        return self.a/self.bclass Factory:                            #簡單工廠，實現(xiàn)各個類實例化交互的過程    def run(self):        op = Operate                       #注意：a,b,operation都是運算父類Operate的 ‘類屬性’ 這樣其子類才能夠直接調(diào)用，子類不能訪問父類的實例屬性        op.a = int(input('plz input the first number:'))        op.operation = input('plz input operation like(+,-,*,/):')        op.b = int(input('plz input the second number:'))                if(op.operation == '+'):            PRint(Add().result())        elif(op.operation == '-'):            print(Subduct().result())        elif(op.operation == '*'):            print(Multiply().result())        elif(operation == '/'):            print(Divide().result())Factory().run()