ThirdParty-6/ParaView-5.0.1/VTK/Web/JavaScript/Widgets/TreeWidget/vtkweb-widget-tree.tpl

<div class='vtkweb-widget-tree'>
  <ul>
      <li class="node">
          <div class="node-line">
              <div class="head"></div>
              <div class="label"></div>
              <div class="tail"></div>
          </div>
          <div class='children'></div>
      </li>
  </ul>
</div>