using System; using System.Collections.Generic; public class OrderedMultiDictionary<T,U> { private RedBlackTree<KeyValuePair<T,U>> tree; private void EnumerateKeys (RedBlackTree<KeyValuePair<T,U>>.RangeTester rangeTester) { tree.EnumerateRange (rangeTester); } } internal class RedBlackTree<S> { public delegate int RangeTester (S item); public void EnumerateRange (RangeTester rangeTester) { } } class X { public static void Main () { } }