code: def cancel_observing(self, response, send_rst):  # pragma: no cover
          
          if send_rst:
              message = Message()
              message.destination = self.server
              message.code = defines.Codes.EMPTY.number
              message.type = defines.Types["RST"]
              message.token = response.token
              message.mid = response.mid
              self.protocol.send_message(message)
          self.stop()
docs: Delete observing on the remote server.
  
          :param response: the last received response
          :param send_rst: if explicitly send RST message
          :type send_rst: bool