public void EnqueueAndDequeue()
{
var q = FingerTree.Empty <int>();
Maybe <int> m;
q = q.EnqueuePrefix(1);
q = q.EnqueuePrefix(2);
q = q.EnqueuePrefix(3);
Expect.IsSome(3, q.CurrentPrefix);
Expect.IsSome(1, q.CurrentSuffix);
(q, m) = q.DequeueSuffix();
Expect.IsSome(1, m);
Expect.IsSome(2, q.CurrentSuffix);
(q, m) = q.DequeueSuffix();
Expect.IsSome(2, m);
Expect.IsSome(3, q.CurrentSuffix);
(q, m) = q.DequeueSuffix();
Expect.IsSome(3, m);
Expect.IsNone(q.CurrentSuffix);
q = q.EnqueuePrefix(4);
q = q.EnqueuePrefix(5);
Expect.IsSome(4, q.CurrentSuffix);
(q, m) = q.DequeueSuffix();
Expect.IsSome(4, m);
Expect.IsSome(5, q.CurrentSuffix);
(q, m) = q.DequeueSuffix();
Expect.IsSome(5, m);
Expect.IsNone(q.CurrentSuffix);
}