public static BookShelf Data(int nToCreate)
        {
            var lret = new BookShelf("private member value")
            {
                Books = Enumerable.Range(1, nToCreate).Select(i => new Book {
                    Id = i, Title = $"Book {i}"
                }).ToList()
            };

            return(lret);
        }
        protected void Init(int count)
        {
            data = BookUtils.Data(10000);

            ssStream = new MemoryStream();
            ServiceStack.Text.JsonSerializer.SerializeToStream(data, ssStream);
            ssJson = ssStream.ReadToEnd();
            ssSpan = ssJson.AsMemory();

            jnStream = new MemoryStream();
            var writer     = new StreamWriter(jnStream, Encoding.UTF8, 1024, leaveOpen: true);
            var jsonWriter = new JsonTextWriter(writer);
            var serializer = new Newtonsoft.Json.JsonSerializer();

            serializer.Serialize(jsonWriter, data);
            jsonWriter.Flush();

            jnJson = jnStream.ReadToEnd();
            $"DATA ServiceStack length = {ssJson.Length}, JSON.NET length = {jnJson.Length}".Print();
        }