flou

This one maybe? https://www.learnenough.com/command-line-tutorial

Seems like you are looking for design-by-contract in Ruby. There is actually a gem for this called contracts : http://egonschiele.github.io/contracts.ruby/

I just recently discovered Spectacle and it's really awesome. It's open source and free, doesn't take up a lot of memory.

http://spectacleapp.com/ https://github.com/eczarny/spectacle