code: def ValidateServiceGaps(self,
                            problems,
                            validation_start_date,
                            validation_end_date,
                            service_gap_interval):
      
      if service_gap_interval is None:
        return
  
      departures = self.GenerateDateTripsDeparturesList(validation_start_date,
                                                        validation_end_date)
  
      # The first day without service of the _current_ gap
      first_day_without_service = validation_start_date
      # The last day without service of the _current_ gap
      last_day_without_service = validation_start_date
  
      consecutive_days_without_service = 0
  
      for day_date, day_trips, _ in departures:
        if day_trips == 0:
          if consecutive_days_without_service == 0:
              first_day_without_service = day_date
          consecutive_days_without_service += 1
          last_day_without_service = day_date
        else:
          if consecutive_days_without_service >= service_gap_interval:
              problems.TooManyDaysWithoutService(first_day_without_service,
                                                 last_day_without_service,
                                                 consecutive_days_without_service)
  
          consecutive_days_without_service = 0
  
      # We have to check if there is a gap at the end of the specified date range
      if consecutive_days_without_service >= service_gap_interval:
        problems.TooManyDaysWithoutService(first_day_without_service,
                                           last_day_without_service,
                                           consecutive_days_without_service)
docs: Validate consecutive dates without service in the feed.
         Issue a warning if it finds service gaps of at least
         "service_gap_interval" consecutive days in the date range
         [validation_start_date, last_service_date)
  
      Args:
        problems: The problem reporter object
        validation_start_date: A date object representing the date from which the
                               validation should take place
        validation_end_date: A date object representing the first day the feed is
                          active
        service_gap_interval: An integer indicating how many consecutive days the
                              service gaps need to have for a warning to be issued
  
      Returns:
        None