public void DeserializeStack()
        {
            string json = @"[
  ""One"",
  ""II"",
  ""3""
]";

            ImmutableStack <string> l = JsonConvert.DeserializeObject <ImmutableStack <string> >(json);

            Assert.AreEqual(3, l.Count());
            Assert.AreEqual("3", l.ElementAt(0));
            Assert.AreEqual("II", l.ElementAt(1));
            Assert.AreEqual("One", l.ElementAt(2));
        }