public async Task <Stream> DownloadGraph(Uri graphName)
        {
            Guard.IsValidUri(graphName);

            var result                 = _graphManagementRepo.GetGraph(graphName);
            var stringAsStream         = new MemoryStream();
            var StreamWriter           = new StreamWriter(stringAsStream);
            CompressingTurtleWriter tw = new CompressingTurtleWriter();

            tw.Save(result, StreamWriter, true);
            StreamWriter.Flush();
            stringAsStream.Position = 0;

            return(stringAsStream);
        }