code: def __sethead(self, access_token):
          
          self.access_token = access_token
          now = calendar.timegm(datetime.datetime.now().timetuple())
          self.expiration = now + 1800
          self.head = {"Authorization": "Bearer %s" % access_token,
                       "User-Agent": self.user_agent
                       }
docs: Set HTTP header.