class Student(object):
    def __init__(self, name, gender):
        self.__name = name
        self.__gender = gender

    def get_name(self):
        return self.__name

    def get_gender(self):
        return self.__gender

    def set_name(self, name):
        if not isinstance(name, str):
            raise ValueError('名称不正确!')
        self.__name = name

    def set_gender(self, gender):
        if gender not in ('male', 'female'):
            raise ValueError('性别错误')
        self.__gender = gender