!== this.items.length) {
          return;
        }

        for (let i = 0; i < this.items.length; i++) {
          if (this.items[i].ref === element) {
            this.selectTreeElement(buttons[i]);
            return;
          }
        }
      }
    }
    customElements.define(TreeView.is, TreeView);
  </script>
</dom-module>