/**
  * Traverse elements to create list from elements.
  *
  * @see Walker::start_el()
  * @since 2.5.0
  *
  * @param object $element Data object
  * @param array $children_elements List of elements to continue traversing.
  * @param int $max_depth Max depth to traverse.
  * @param int $depth Depth of current element.
  * @param array $args
  * @param string $output Passed by reference. Used to append additional content.
  * @return null Null on failure with no changes to parameters.
  */
 public function display_element($element, &$children_elements, $max_depth, $depth, $args, &$output)
 {
     if (!$element) {
         return;
     }
     //If parent is not current item, don't output children
     if (!$element->current) {
         parent::unset_children($element, $children_elements);
     }
     parent::display_element($element, $children_elements, $max_depth, $depth, $args, $output);
 }