code: function (rootNode) {
          if (!this._parent) {
              return '/';
          }
  
          var current = this._parent;
          var path = this.name;
          while (current._parent) {
              path = current.name + '/' + path;
              if (current._parent == rootNode) {
                  break;
              }
              current = current._parent;
          }
          if (!current._parent && rootNode) {
              return null;
          }
          return path;
      }
docs: Get query path, relative to rootNode(default is scene)
  @param {clay.Node} [rootNode]
  @return {string}