Xpressengine\Routing\RouteRepository::findByInstanceId PHP Method

    public function findByInstanceId($instanceId);

 /**
  * Retrieve a route by instance identifier
  *
  * @param string $instanceId instance identifier
  * @return InstanceRoute
  */
 public function findByInstanceId($instanceId)
 {
     if (!array_key_exists($instanceId, $this->mapByInstanceId)) {
         if (!($route = $this->repo->findByInstanceId($instanceId))) {
             return null;
         }
         $this->setToMap($route);
     }
     return $this->mapByInstanceId[$instanceId];
 }