protected override Task <long> ReadHeadPositionInternal(CancellationToken cancellationToken)
        {
            var message = _allStream.LastOrDefault();

            return(message == null?Task.FromResult(-1L) : Task.FromResult(message.Position));
        }
        protected override Task <long> ReadHeadCheckpointInternal(CancellationToken cancellationToken)
        {
            var streamEvent = _allStream.LastOrDefault();

            return(streamEvent == null?Task.FromResult(-1L) : Task.FromResult(streamEvent.Checkpoint));
        }