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