David Beazley is using Scheme! That is a nice shift towards a civilized language. I hope he scraps the scheme-in-python section, but perhaps that is intended as an exit drug for Python addicts.
I'd rather see FP addicts exit Python ecosystem. I had dubious pleasure of working with Python codebases written by FP enthusiasts. It was hell. Simple, well-understood problem domains were made way more complex by introduction of GraphQL and FP resulting in about a dozen levels of nesting for something that could have been a simple FastAPI app.