docs: def return_real_id_base(dbpath, set_object):
      """
      Generic function which returns a list of real_id's
  
      Parameters
      ----------
      dbpath : string, path to SQLite database file
      set_object : object (either TestSet or TrainSet) which is stored in the database
  
      Returns
      -------
      return_list : list of real_id values for the dataset (a real_id is the filename minus the suffix and prefix)
      """
      engine = create_engine('sqlite:////' + dbpath)
      session_cl = sessionmaker(bind=engine)
      session = session_cl()
      return_list = []
      for i in session.query(set_object).order_by(set_object.id):
          return_list.append(i.real_id)
      session.close()
      return return_list