public static Task WriteAsync(this Stream stream, byte[] bytes, int offset, int count, CancellationToken cancellationToken = default(CancellationToken))
{
var factory = cancellationToken.Equals(default(CancellationToken))
? Task.Factory
: new TaskFactory(cancellationToken);
return factory.FromAsync(stream.BeginWrite, stream.EndWrite, bytes, offset, count, null);
}
