public function getNextSibling()
	{
		$left = $this->getRightValue() + 1;
		$searchCondition = $this->repository->createSearchCondition()
				->leftEqualsTo($left);

		$nextSibling = $this->repository->search($searchCondition);
		if ( ! isset($nextSibling[0])) {
			return null;
		}
		$nextSibling = $nextSibling[0];
		
		return $nextSibling;
	}