/**
  * Get childs of node
  *
  * @param int $a_parent_id parent id
  * @return array childs
  */
 function getChildsOfNode($a_parent_id)
 {
     switch (ilSkillTreeNode::_lookupType($a_parent_id)) {
         /*
               'id' => string '1' (length=1)
               'skill_id' => string '4' (length=1)
               'nr' => string '1' (length=1)
               'title' => string 'Ungenügend' (length=11)
               'description' => null
               'trigger_ref_id' => string '0' (length=1)
               'trigger_obj_id' => string '0' (length=1)
         */
         default:
             $childs = parent::getChildsOfNode($a_parent_id);
             //var_dump($childs);
             return $childs;
     }
 }