I don't. I'm not sure it would be that interesting.

In short:

* I started out with a class that substituted environment variables into itself for settings, still in aiohttp-devtools: https://github.com/aio-libs/aiohttp-devtools/blob/master/aio...

* using annotations occurred to me

* it worked

* it was 50% faster than trafaret which I'd been using before

* I added some unit tests, published to pypi and started using it.