public static Uri Combine(this Uri uri, Uri fragment)
{
if (fragment.IsAbsoluteUri)
return fragment;
string fragment1 = uri.Fragment;
string fragment2 = fragment.ToString();
if (!fragment1.EndsWith("/"))
fragment1 = fragment1 + '/';
if (fragment2.StartsWith("/"))
fragment2 = fragment2.Substring(1);
return new Uri(uri, fragment1 + fragment2);
}