ags"></span></div></div></div></div><div class="qm-api-collapsible-content"><div class="qm-api-item-content"><div class="qm-api-description"><div class="qm-html-paragraph">The class to give to tree elements. When building trees using the  <code class="qm-code-highlight-code qm-code-font">items</code>  method, these classes will be added to content automatically. </div></div><div class="qm-api-group qm-api-class-group"><div class="qm-api-group-header qm-api-class-group-header qm-header-font">Classes</div><di