function fetchGroupTree($parentGroupID, $sortBy, $offset, $limit, $depth)
 {
     $treeParameters = array('parent_group_id' => $parentGroupID, 'offset' => $offset, 'limit' => $limit, 'sort_by' => $sortBy, 'depth' => $depth);
     $children = eZCollaborationGroup::subTree($treeParameters);
     if ($children === null) {
         return array('error' => array('error_type' => 'kernel', 'error_code' => eZError::KERNEL_NOT_FOUND));
     }
     return array('result' => $children);
 }