def GetTimeSecs(self):
    if self.arrival_secs != None:
      return self.arrival_secs
    elif self.departure_secs != None:
      return self.departure_secs
    else:
      return None
Return the first of arrival_secs and departure_secs that is not None.
dataset/ETHPy150Open google/transitfeed/transitfeed/stoptime.py/StopTime.GetTimeSecs