code: def _poll(self, future):
          
  
          if future._poll_backoff is None:
              # on first poll, start with minimal back-off
              future._poll_backoff = self._POLL_BACKOFF_MIN
  
              # if we have ETA of results, schedule the first poll for then
              if future.eta_min and self._is_clock_diff_acceptable(future):
                  at = datetime_to_timestamp(future.eta_min)
                  _LOGGER.debug("Response ETA indicated and local clock reliable. "
                                "Scheduling first polling at +%.2f sec", at - epochnow())
              else:
                  at = time.time() + future._poll_backoff
                  _LOGGER.debug("Response ETA not indicated, or local clock unreliable. "
                                "Scheduling first polling at +%.2f sec", at - epochnow())
  
          else:
              # update exponential poll back-off, clipped to a range
              future._poll_backoff = \
                  max(self._POLL_BACKOFF_MIN,
                      min(future._poll_backoff * 2, self._POLL_BACKOFF_MAX))
  
              # for poll priority we use timestamp of next scheduled poll
              at = time.time() + future._poll_backoff
  
          now = utcnow()
          future_age = (now - future.time_created).total_seconds()
          _LOGGER.debug("Polling scheduled at %.2f with %.2f sec new back-off for: %s (future's age: %.2f sec)",
                        at, future._poll_backoff, future.id, future_age)
  
          # don't enqueue for next poll if polling_timeout is exceeded by then
          future_age_on_next_poll = future_age + (at - datetime_to_timestamp(now))
          if self.polling_timeout is not None and future_age_on_next_poll > self.polling_timeout:
              _LOGGER.debug("Polling timeout exceeded before next poll: %.2f sec > %.2f sec, aborting polling!",
                            future_age_on_next_poll, self.polling_timeout)
              raise PollingTimeout
  
          self._poll_queue.put((at, future))
docs: Enqueue a problem to poll the server for status.