public User UndoMerge(AggregateStore <int> store, int userID, int mergeID)
        {
            var user   = User.Blank();
            var events = store.Replay("Users", userID);
            var mergeTransformations = new List <Transformation>();

            user.LoadFromEvents(events.Apply(e =>
            {
                var asMerge      = e as IMergeEvent;
                var isMergeEvent = asMerge != null && asMerge.MergeID == mergeID;

                if (isMergeEvent)
                {
                    MergeEvent(user, mergeTransformations, mergeID, e);
                }
            }));

            mergeTransformations
            .Where(t => t.HasChangedSinceMerge() == false)
            .Select(t => t.UndoEvent)
            .ForEach(e => user.PushEvent(e));

            return(user);
        }