def bind(self, app: flask.Flask):
    app.add_url_rule('/about', view_func=self.about)
    app.add_url_rule('/users/', view_func=self.get_users)
    app.add_url_rule('/users/<id>', view_func=self.get_user)
    app.add_url_rule('/users/', view_func=self.add_user, methods=['POST'])
    app.add_url_rule('/users/<id>', view_func=self.del_user, methods=['DELETE'])
    app.add_url_rule('/users/<id>/avatar', view_func=self.get_user_avatar, methods=['GET'])
    app.add_url_rule('/users/<id>/avatar', view_func=self.update_user_avatar, methods=['PUT'])
def bind(self, app: flask.Flask):
    app.add_url_rule('/about', view_func=self.about)
    app.add_url_rule('/users/', view_func=self.get_users)
    app.add_url_rule('/users/<id>', view_func=self.get_user)
    app.add_url_rule('/users/', view_func=self.add_user, methods=['POST'])
    app.add_url_rule('/users/<id>', view_func=self.del_user, methods=['DELETE'])
    app.add_url_rule('/users/<id>/avatar', view_func=self.get_user_avatar, methods=['GET'])
    app.add_url_rule('/users/<id>/avatar', view_func=self.update_user_avatar, methods=['PUT'])