System.util.collections.OrderedTree.GetData C# (CSharp) Method

        public object GetData(IComparable key)
        {
            if(key == null)
                throw new ArgumentNullException("Key is null");
            int result;

            OrderedTreeNode treeNode = rbTree; // begin at root

            // traverse tree until node is found
            while(treeNode != sentinelNode) {
                result = key.CompareTo(treeNode.Key);
                if(result == 0) {
                    lastNodeFound = treeNode;
                    return treeNode.Data;
                }
                if(result < 0)
                    treeNode = treeNode.Left;
                else
                    treeNode = treeNode.Right;
            }
            return null;
        }