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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 AddStop(self, lat, lng, name, stop_id=None):
 """Add a stop to this schedule. Args: lat: Latitude of the stop as a float or string lng: Longitude of the stop as a float or string name: Name of the stop, which will appear in the feed stop_id: stop_id of the stop or None, in which case a unique id is picked Returns: A new Stop object """

    if stop_id is None:
      stop_id = util.FindUniqueId(self.stops)
    stop = self._gtfs_factory.Stop(stop_id=stop_id, lat=lat, lng=lng, name=name)
    self.AddStopObject(stop)
    return stop