How to Make Commands on Interfaces

I'm struggling right now to keep another library of mine small which is Click. Click is basically a micro framework for making commands on applications. It's based on similar ideas as Flask in a way and it's very composable. You make a Click application and you can attach another Click application to another Click application. That's really amazing. Sure I think that's probably attributable to the fact that you kept it small and didn't try to make everybody build on your APIs but kind of passed through.