private void RBAssertPresent(RedBlackTree<int, string> rb, int s, int e)
{
for (int i = s; i <= e; i++) {
IList<string> result = rb.Search(i);
Assert.AreEqual(1, result.Count, string.Format("#{0}->{1}@{2}", s, e, i));
Assert.AreEqual(i.ToString(), result[0], string.Format("#{0}->{1}@{2}", s, e, i));
}
}