Click is a Python package for creating beautiful command line interfaces in a composable way with as little code as necessary. It's the "Command Line Interface Creation Kit". It's highly configurable
Hmm, I wonder how it compares to Traitlets? I got recommended that and it's taken me a while to learn, but it is very powerful. I'm just starting on a subcommand based app, so this is very relevant to me!
EDIT: Just glancing at the documentation I can see the docs are way better!