private void BuildTree(TreeData root, List <SearchCluster> clusters)
        {
            if (clusters != null)
            {
                foreach (SearchCluster cluster in clusters)
                {
                    TreeData treeData = new TreeData(cluster.Title, cluster.Score, cluster);

                    root.Add(treeData);

                    BuildTree(treeData, cluster.SearchClusters);
                }
            }
        }