public async Task Summarize()
        {
            TextAnalysisClient Client = new TextAnalysisClient(Config.TextAnalysisApiKey);

            string        fname = @"Data\wap.txt";
            StorageFolder InstallationFolder = Windows.ApplicationModel.Package.Current.InstalledLocation;
            var           file = await InstallationFolder.GetFileAsync(fname);

            var stream = await file.OpenReadAsync();

            var sr = new StreamReader(stream.AsStreamForRead());
            int b  = 0; // BOOK
            int c  = 0; // Chapter
            int p  = 0; // Paragraph

            StringBuilder             sb    = new StringBuilder();
            TextAnalysisDocumentStore Store = new TextAnalysisDocumentStore();

            while (!sr.EndOfStream)
            {
                var s = await sr.ReadLineAsync();

                if (s.Contains("BOOK"))
                {
                    b++;
                    c = 0;
                    if (b > 2)
                    {
                        break;
                    }
                    continue;
                }
                if (s.Contains("CHAPTER"))
                {
                    if (sb.Length > 20)
                    {
                        var key = $"b{b}c{c}p{p}";
                        Store.documents.Add(new TextAnalysisDocument(key, "en", sb.ToString()));
                    }
                    sb.Clear();
                    if (Store.documents.Count > 0)
                    {
                        var R = await Client.ExtractKeyphrases(Store);

                        StringBuilder z = new StringBuilder();
                        z.AppendLine($"CHAPTER {c}");
                        foreach (var d in R.documents)
                        {
                            z.AppendLine(string.Join(",", d.keyPhrases));
                        }
                        Summary.Text += z.ToString();
                    }
                    Store.documents.Clear();
                    c++;
                    p = 0;
                    continue;
                }
                if (s.Trim().Equals(string.Empty))
                {
                    if (sb.Length > 20)
                    {
                        var key = $"b{b}c{c}p{p}";
                        if (Store.documents.Count > 0 && Store.documents.Last().text.Length + sb.ToString().Length < 5000)
                        {
                            System.Diagnostics.Debug.WriteLine($"Last {Store.documents.Last().text.Length}, sb {sb.Length}");
                            Store.documents.Last().text += "\n\r" + sb.ToString();
                        }
                        else
                        {
                            Store.documents.Add(new TextAnalysisDocument(key, "en", sb.ToString()));
                        }
                    }
                    sb.Clear();
                    p++;
                    continue;
                }
                sb.AppendLine(s);
            }
        }