code: def to_unix_ts(start_time):
      
      if isinstance(start_time, datetime):
          if is_timezone_aware(start_time):
              start_time = start_time.astimezone(pytz.utc)
          else:
              log.warning(
                  "Non timezone-aware datetime object passed to IncrementalEndpoint. "
                  "The Zendesk API expects UTC time, if this is not the case results will be incorrect!"
              )
          unix_time = calendar.timegm(start_time.timetuple())
      else:
          unix_time = start_time
  
      return int(unix_time)
docs: Given a datetime object, returns its value as a unix timestamp