from abc import ABC,abstractmethod
class concrete():
    @abstractmethod
    def w1(self):
        pass 
    @abstractmethod
    def r1(self):
        pass 
class derived(concrete):
    def w1(self):
            self.a=10
    def r1(self): 
            print(self.a)
D=derived()
D.w1() 
D.r1()