public void TestMultiMapAdd()
        {
            MultiMapList <string, string> multiMapList = new MultiMapList <string, string>();
            string key  = nameof(key);
            string val  = nameof(val);
            string val2 = nameof(val2);

            Assert.IsTrue(multiMapList.TryToAddMapping(key, val));
            Assert.IsTrue(multiMapList.TryToAddMapping(key, val));
            Assert.IsTrue(multiMapList.TryToAddMapping(key, val2));
            Assert.IsTrue(multiMapList.TryToAddMapping(key, val2));
            Assert.AreEqual(2, multiMapList.ContainsMapping(key, val));
            Assert.AreEqual(2, multiMapList.ContainsMapping(key, val2));
        }
        public void TestMultiMapRemove()
        {
            MultiMapList <string, string> multiMapList = new MultiMapList <string, string>();
            string key  = nameof(key);
            string val  = nameof(val);
            string val2 = nameof(val2);

            Assert.IsTrue(multiMapList.TryToAddMapping(key, val));
            Assert.IsTrue(multiMapList.TryToAddMapping(key, val));
            Assert.IsTrue(multiMapList.TryToAddMapping(key, val2));
            Assert.IsTrue(multiMapList.TryToAddMapping(key, val2));
            Assert.AreEqual(2, multiMapList.ContainsMapping(key, val));
            Assert.AreEqual(2, multiMapList.ContainsMapping(key, val2));

            Assert.IsTrue(multiMapList.TryToRemoveMapping(key, val));
            Assert.AreEqual(1, multiMapList.ContainsMapping(key, val));
            Assert.IsTrue(multiMapList.TryToRemoveMapping(key, val));
            Assert.IsFalse(multiMapList.TryToRemoveMapping(key, val));
            Assert.AreEqual(0, multiMapList.ContainsMapping(key, val));
            Assert.AreEqual(1, multiMapList.Keys.Count);
            Assert.AreEqual(1, multiMapList.Values.Count);


            Assert.IsTrue(multiMapList.TryToRemoveMapping(key, val2));
            Assert.AreEqual(1, multiMapList.ContainsMapping(key, val2));
            Assert.IsTrue(multiMapList.TryToRemoveMapping(key, val2));
            Assert.IsFalse(multiMapList.TryToRemoveMapping(key, val2));
            Assert.AreEqual(0, multiMapList.ContainsMapping(key, val2));

            Assert.AreEqual(0, multiMapList.Keys.Count);
            Assert.AreEqual(0, multiMapList.Values.Count);
        }