我有模型：class User(db.Model, UserMixin):    id = db.Column(db.Integer, primary_key = True)    login = db.Column(db.String(20), unique = True, nullable = False)    username = db.Column(db.String(200), nullable = True)    password = db.Column(db.String(60), nullable = False)    user_level = db.Column(db.Integer, nullable = False)    parent_id = db.Column(db.Integer, db.ForeignKey('user.id'))    terminals = db.relationship('Terminal', backref='owner', lazy = True)    controled_users = db.relationship('User', backref=db.backref('parent', remote_side=[id]), lazy = True)    def get_children_list(self) -> []:        beginning_getter = db.session.query(User).\                filter(User.id == id).cte(name='children_for', recursive=True)        with_recursive = beginning_getter.union_all(                db.session.query(User).filter(User.parent_id == beginning_getter.c.id)            )        return db.session.query(with_recursive).all()    def __repr__(self):        return "User('{0}')".format(self.username)所以每個人都User可以有孩子用戶的什么可以有自己的孩子。我試圖獲取所有孩子的列表：current_user.get_children_list()在這里找不到什么問題？