public void TailTest()
        {
            const string data = "How now, brown cow?";
            var          list = data.Split().Aggregate(SkewBinaryRandomAccessList <string> .Empty, (current, word) => SkewBinaryRandomAccessList <string> .Cons(word, current));

            list = SkewBinaryRandomAccessList <string> .Tail(list);

            Assert.AreEqual("brown", SkewBinaryRandomAccessList <string> .Lookup(0, list));
            Assert.AreEqual("now,", SkewBinaryRandomAccessList <string> .Lookup(1, list));
            Assert.AreEqual("How", SkewBinaryRandomAccessList <string> .Lookup(2, list));
        }
        public void EmptyTailTest()
        {
            var list = SkewBinaryRandomAccessList <string> .Empty;

            AssertThrows <ArgumentNullException>(() => SkewBinaryRandomAccessList <string> .Tail(list));
        }