Try win32 2.0.2

Thanks for your support of my package! 

I've added the named pipe and other APIs that you're using that were missing from win32. If you bump up to this version, you should be able to retire your `Win32Additional` class.

https://pub.dev/packages/win32/versions/2.0.2 

Let me know if there's anything else that I can add to help you out!