抽象方法

import abc


class Student(metaclass=abc.ABCMeta):

    @abc.abstractmethod
    def get_radius(self):
        raise Exception('xxxxxxxxx')


class Student2(Student):
    # 必须要重写此方法
    def get_radius(self):
        pass


s = Student2()
if __name__ == '__main__':
    print(12)