code: def add_url_rule(self, host, rule_string, endpoint, **options):
          
          rule = Rule(rule_string, host=host, endpoint=endpoint, **options)
          self.url_map.add(rule)
docs: Add a url rule to the app instance.
  
          The url rule is the same with Flask apps and other Werkzeug apps.
  
          :param host: the matched hostname. e.g. "www.python.org"
          :param rule_string: the matched path pattern. e.g. "/news/<int:id>"
          :param endpoint: the endpoint name as a dispatching key such as the
                           qualified name of the object.