flask 匿名用户自定义类 AnonymousUser 无法调用

model 中自定义了 AnonymousUser 类：

class MyAnonymousUser(AnonymousUserMixin):

def can(self, permissions):

    return False

def is_administrator(self):

    return False

login_manager.anonymous_user = MyAnonymousUser

在视图函数中使用了 can 方法：

@main.route('/', methods=['GET', 'POST'])

def index():

form = PostForm()

if current_user.can(Permission.WRITE_ARTICLES) and form.validate_on_submit():

    post = Post(body=form.body.data,

                author=current_user._get_current_object())

结果运行出现'AnonymousUserMixin' object has no attribute 'can'的错误，请问下问题出在哪里？登录用户能够正常调用角色验证方法。