private Value get(STNode<Key, Value> x, Key key)
	{
		while (x != null)
		{
			int cmp = key.compareTo(x.key);
			if (cmp < 0)
				x = x.left;
			else if (cmp > 0)
				x = x.right;
			else
				// cmp == 0
				return x.val;
		}
		return null;
	}