code: def last_edit_time(self):
          
          data = {'_xsrf': self.xsrf, 'offset': '1'}
          res = self._session.post(self.url + 'log', data=data)
          _, content = res.json()['msg']
          soup = BeautifulSoup(content)
          time_string = soup.find_all('time')[0]['datetime']
          return datetime.strptime(time_string, "%Y-%m-%d %H:%M:%S")
docs: :return: 问题最后编辑时间
          :rtype: datetime.datetime