vulture does a decent job at this. clippy does an amazing job at this.

We don't want to emit this for 'public' methods. I don't know if we just want to check __all__, or if we want to be more lenient, personally I think an option to say I don't want to export anything, so the rule is very pedantic would be great, and the other side of that is maybe only complaining about 'private' (prefixed with '_') methods that are unused.