public static string realpath(string path)
{
if (string.IsNullOrEmpty(path))
return null;
// string ending slash
if (path[path.Length - 1].IsDirectorySeparator())
path = path.Substring(0, path.Length - 1);
string realpath = AbsolutePath(path);
throw new NotImplementedException();
//if (!File.Exists(realpath) && !System.IO.Directory.Exists(realpath))
//{
// return null;
//}
//return realpath;
}