code: def keep_alive_timeout_callback(self):
          
          time_elapsed = time() - self._last_response_time
          if time_elapsed < self.keep_alive_timeout:
              time_left = self.keep_alive_timeout - time_elapsed
              self._keep_alive_timeout_handler = self.loop.call_later(
                  time_left, self.keep_alive_timeout_callback
              )
          else:
              logger.debug("KeepAlive Timeout. Closing connection.")
              self.transport.close()
              self.transport = None
docs: Check if elapsed time since last response exceeds our configured
          maximum keep alive timeout value and if so, close the transport
          pipe and let the response writer handle the error.
  
          :return: None