Add a route to this schedule.

    Args:
      short_name: Short name of the route, such as "71L"
      long_name: Full name of the route, such as "NW 21st Ave/St Helens Rd"
      route_type: A type such as "Tram", "Subway" or "Bus"
      route_id: id of the route or None, in which case a unique id is picked
    Returns:
      A new Route object

def AddRoute(self, short_name, long_name, route_type, route_id=None):
    """Add a route to this schedule.

    Args:
      short_name: Short name of the route, such as "71L"
      long_name: Full name of the route, such as "NW 21st Ave/St Helens Rd"
      route_type: A type such as "Tram", "Subway" or "Bus"
      route_id: id of the route or None, in which case a unique id is picked
    Returns:
      A new Route object
    """
    if route_id is None:
      route_id = util.FindUniqueId(self.routes)
    route = self._gtfs_factory.Route(short_name=short_name, long_name=long_name,
                        route_type=route_type, route_id=route_id)
    route.agency_id = self.GetDefaultAgency().agency_id
    self.AddRouteObject(route)
    return route