private boolean isRankConsistent(STNode<Key, Value> x)
	{
		for (int i = 0; i < size(x); i++)
			if (i != rank(select(i)))
			{
				return false;
			}
		for (Key key : keys())
			if (key.compareTo(select(rank(key))) != 0)
				return false;
		return true;
	}