[Web-SIG] why function throws an error?

[נתי שטרן‎]

        def add_route(self, route):

        #    """ Add a route object, but do not change the :data:`Route.app`

        #        attribute."""

            self.routes.append(route)

            self.router.add(route.rule, route.method, route, name=route.name)

        #    if DEBUG: route.prepare()

--