RadixTree.Tree.FindPredecessorRec C# (CSharp) Method

        private string FindPredecessorRec(string wordPart, Node curNode,string carry)
        {
            var matches = MatchingConsecutiveCharacters(wordPart, curNode);

            if ((matches == 0) || (curNode == _root) ||
                ((matches > 0) && (matches < wordPart.Length) && (matches >= curNode.Label.Length)))
            {

                var newLabel = wordPart.Substring(matches, wordPart.Length - matches);
                foreach (var child in curNode.SubNodes)
                    if (child.Label.StartsWith(newLabel[0].ToString()))
                        return FindPredecessorRec(newLabel, child, carry + curNode.Label);

                return carry + curNode.Label;
            }
            else if (matches == curNode.Label.Length)
            {
                return carry + curNode.Label;
            }
            else return string.Empty;
        }