private Task <Validation <BaseError, Unit> > FolderMustBeEmpty(StartFFmpegSession request) { string folder = Path.Combine(FileSystemLayout.TranscodeFolder, request.ChannelNumber); _logger.LogDebug("Preparing transcode folder {Folder}", folder); _localFileSystem.EnsureFolderExists(folder); _localFileSystem.EmptyFolder(folder); return(Task.FromResult <Validation <BaseError, Unit> >(Unit.Default)); }