#!/usr/bin/env python3
# -*- coding: utf-8 -*-
class Student(object):
    def __init__(self, name, gender):
        self.__name = name
        self.__gender = gender
    
    def get_gender(self):
        return self.__gender
    
    def set_gender(self, s):
        if s in ('male', 'female'):
            self.__gender = s
        else:
            print('请输入字符串。')
    

# 测试:
bart = Student('Bart', 'male')
if bart.get_gender() != 'male':
    print('测试失败!')
else:
    bart.set_gender('female')
    if bart.get_gender() != 'female':
        print('测试失败!')
    else:
        print('测试成功!')