public void EasyDequeTest()
        {
            var deQ = new EasyDeque <int>();

            deQ.AddToHead(1);
            deQ.AddToTail(2);
            deQ.AddToHead(3);
            deQ.AddToTail(4);

            Assert.AreEqual(3, deQ.GetFromHead());
            Assert.AreEqual(4, deQ.GetFromTail());

            deQ.GetFromTail();
            deQ.GetFromTail();
            Assert.ThrowsException <InvalidOperationException>(() => deQ.GetFromHead());
        }