class Student(object):    def __init__(self,name,gender):        self.name=name        self.__gender=gender    def get_gender(self):        # if gender!='male':        #     print('测试失败')        # else:        return self.__gender    def set_gender(self,gender):        if gender != 'female':            print('测试失败')        else:            self.__gender=genderbart=Student('Bart','male')print(bart.get_gender())bart.set_gender('female')print(bart.get_gender())