public void AddMarker()
        {
            _liveSequence.Subscribe();
            _liveSequence.Add(Completable.Never());
            _liveSequence.AddAction(Assert.Fail);
            var instant = _liveSequence.AddInstant();

            _liveSequence.AddAction(() => _value = 2);

            AssertValue(0);
            _liveSequence.SkipBefore(instant);
            AssertValue(2);
        }