code: def add_ping(self, rule, status_code=200, app=None):
          
          app = self._get_app(app)
  
          @app.route(rule)
          def ping():
              return '', status_code
docs: Add a ping route.
  
          :param str rule: The URL rule. This will not use the API prefix, as the
              ping endpoint is not really part of the API.
          :param int status_code: The ping response status code. The default is
              200 rather than the more correct 204 because many health checks
              look for 200s.
          :param app: If specified, the application to which to add the route.
              Otherwise, this will be the bound application, if present.