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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def GetTimeSecs(self):
 """Return the first of arrival_secs and departure_secs that is not None. If both are None return None."""

    if self.arrival_secs != None:
      return self.arrival_secs
    elif self.departure_secs != None:
      return self.departure_secs
    else:
      return None