@classmethod
def query_active_stop_ids(cls, session, limit=None, active_filter=True):
    """
        return an array of stop_id / agencies pairs
        {stop_id:'2112', agencies:['C-TRAN', 'TRIMET']}
        """
    ret_val = []
    stops = cls.query_active_stops(session, limit, active_filter)
    for s in stops:
        ret_val.append({'stop_id': s.stop_id, 'agencies': s.agencies})
    return ret_val
