function fetchList($collaborationID, $userID = false, $asObject = true)
 {
     if ($userID == false) {
         $userID == eZUser::currentUserID();
     }
     return eZPersistentObject::fetchObjectList(eZCollaborationItemGroupLink::definition(), null, array('collaboration_id' => $collaborationID, 'user_id' => $userID), null, null, $asObject);
 }