public void RefCount()
        {
            var ms = new MaybeSubject <int>(true);

            var sad = new SingleAssignmentDisposable();

            ms.OnSubscribe(sad);

            Assert.False(sad.IsDisposed());

            var to = ms.Test();

            Assert.False(sad.IsDisposed());

            var to2 = ms.Test(true).AssertSubscribed().AssertEmpty();

            Assert.False(sad.IsDisposed());

            to.Dispose();

            Assert.True(sad.IsDisposed());

            ms.Test().AssertFailure(typeof(OperationCanceledException));
        }