code: def send_message(self, author, content):
          
          if isinstance(author, Author) is False:
              raise ValueError('argument answer need to be Zhihu.Author object.')
          if not content:
              raise ValueError('answer content cannot be empty')
          if author.url == self.url:
                  return False
          data = {
              'member_id': author.hash_id,
              'content': content,
              'token': '',
              '_xsrf': author.xsrf
          }
          res = self._session.post(Send_Message_Url,
                                   data=data)
          return res.json()['r'] == 0
docs: 发送私信给一个用户
  
          :param Author author: 接收私信用户对象
          :param string content: 发送给用户的私信内容
          :return: 成功返回 True，失败返回 False
          :rtype: bool