from abc import ABC,abstractmethod
class A(ABC):
    @abstractmethod
    def read(self):
        pass
    @abstractmethod
    def write(self):
        pass
    def read1(self):
        self.b=20
    def write1(self):
        print(self.b)
class B(A):
    def read(self):
        self.a=10
    def write(self):
        print(self.a)
b=B()
b.read()
b.write()
b.read1()
b.write1()