public static async Task SaveStreamToFile(Windows.Storage.Streams.IRandomAccessStream stream, Windows.Storage.IStorageFile file)
{
using var fileStream = await file.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);
var buffer = new byte[stream.Size];
var ibuffer = buffer.AsBuffer();
stream.Seek(0);
await stream.ReadAsync(ibuffer, (uint)stream.Size, Windows.Storage.Streams.InputStreamOptions.None);
await fileStream.WriteAsync(ibuffer);
}