code: def CheckDisjointCalendars(self):
      
      # TODO: Do an exact check here.
  
      a_service_periods = self.feed_merger.a_schedule.GetServicePeriodList()
      b_service_periods = self.feed_merger.b_schedule.GetServicePeriodList()
  
      for a_service_period in a_service_periods:
        a_start, a_end = a_service_period.GetDateRange()
        for b_service_period in b_service_periods:
          b_start, b_end = b_service_period.GetDateRange()
          overlap_start = max(a_start, b_start)
          overlap_end = min(a_end, b_end)
          if overlap_end >= overlap_start:
            return False
      return True
docs: Check whether any old service periods intersect with any new ones.
  
      This is a rather coarse check based on
      transitfeed.SevicePeriod.GetDateRange.
  
      Returns:
        True if the calendars are disjoint or False if not.