public void TestDictionaryBasedWith1()
        {
            IndexMap map = new IndexMap.DictionaryBased();

            map = map.Add(0, 1);
            Assert.AreEqual(1, map.Map(0));
            Assert.Throws <KeyNotFoundException>(() => map.Map(1));
        }
        public void TestDictionaryBasedWith0()
        {
            var map = new IndexMap.DictionaryBased();

            Assert.Throws <KeyNotFoundException>(() => map.Map(0));
        }