despec.module

<?php
function bootstrap_views_tree_inner($variables) {
  $view = $variables['view'];
  $options = $variables['options'];
  $rows = $variables['rows'];
  $title = $variables['title'];
  $result = $variables['result'];
  $parent = $variables['parent'];

  // Assuming that the first parent is always 0 (root level), we can initialize
  // the depth variable.
  $variables['depth'] = $parent == 0 ? 0 : $variables['depth'] + 1;
  // Set the depth limit to whatever suits you. You can set different depth
  // limits by switching on the view name and display.
  $depth_limit = 1;
  $items = array();
  if ($depth_limit >= $variables['depth']) {
    foreach ($result as $i => $record) {
      if ($record->views_tree_parent == $parent) {
        $variables['parent'] = $record->views_tree_main;
        $items[] = $rows[$i] . call_user_func(__FUNCTION__, $variables);
      }
    }
  }
  return count($items) ? theme('item_list', array('items' => $items, 'type' => $options['type'])) : '';
}