code: def _get_business_hours_by_sec(self):
          
          if self._get_daytime_flag:
              # create dummy datetime to calculate businesshours in a day
              dtstart = datetime(2014, 4, 1, self.start.hour, self.start.minute)
              until = datetime(2014, 4, 1, self.end.hour, self.end.minute)
              return (until - dtstart).total_seconds()
          else:
              dtstart = datetime(2014, 4, 1, self.start.hour, self.start.minute)
              until = datetime(2014, 4, 2, self.end.hour, self.end.minute)
              return (until - dtstart).total_seconds()
docs: Return business hours in a day by seconds.