调用__write_user函数,写入json文件中的"create_time"，"update_time"为什么不是格式化的字符串

if __name__ == '__main__':
# 获取gift.json和user.json的路径
    gift_path = os.path.join(os.getcwd(), 'storage', 'gift.json')
    user_path = os.path.join(os.getcwd(), 'storage', 'user.json')
# print(gift_path, user_path)
    # 实例化
    base = Base(user_json=user_path, gift_json=gift_path)
    base._Base__write_user(username='dewei', role='admin')  # 调用私有函数,写入一个user信息
    print(base._Base__read_users())  # 调用私有函数,读出一个user信息

'''读出JSON文件，如果time_to_string=True则将时间戳转换成格式化字符串'''
def __read_users(self, time_to_string=True):
with open(self.user_json, 'r')as f:
# 反序列化,返回原始数据类型
        data = json.loads(f.read())
if time_to_string is True:
for username, value in data.items():
            value['create_time'] = timestamp_to_string(value['create_time'])
            value['update_time'] = timestamp_to_string(value['update_time'])
            data[username] = value
return data  # 字典

# 写入user的相关信息
def __write_user(self, **user):
# **user:将有参数与默认值的赋值语句合并成字典
    if 'username' not in user:
raise ValueError('Missing username')
if 'role' not in user:
raise ValueError('Missing role')
# 默认active为True
    user['active'] = True
    # 初始的创建时间和更新时间相同
    user['create_time'] = time.time()
    user['update_time'] = time.time()
# 默认gifts为空列表
    user['gifts'] = []

""""
    users来自user.json文件
    {username:{username:xxx,role:xxx,active:xxx,...}}
    username为key来检索用户信息
    
    user来自参数**user
    {username:xxx, role:xxx, active:xxx,...}
    """
    users = self.__read_users(time_to_string=True)  # 返回字典

    '''如果将要添加的username已存在user.json文件中'''
    if user['username'] in users:
raise UserExistsError('username %s had exists' % user['username'])
# 写入
    users.update(
        {user['username']: user}
    )
# 序列化并写入
    json_users = json.dumps(users)
with open(self.user_json, 'w')as f:
        f.write(json_users)