public function doesPublicIdExist($id, Tree $tree)
 {
     if ($tree->getId()) {
         $tvs = $this->getEntityManager()->createQuery(' SELECT tv FROM QuestionKeyBundle:TreeVersion tv' . ' WHERE tv.tree = :tree AND tv.publicId = :public_id')->setParameter('tree', $tree)->setParameter('public_id', $id)->getResult();
         return (bool) $tvs;
     } else {
         return false;
     }
 }