code: def by_group_name(cls, group_name, db_session=None):
          
          db_session = get_db_session(db_session)
          query = db_session.query(cls.model).filter(cls.model.group_name == group_name)
          return query.first()
docs: fetch group by name
  
          :param group_name:
          :param db_session:
          :return: