What's your favourite GitHub Gist?

There are those ideas/things which, yet being simple, awe you with their elegance. The following GitHub Gist, conveying the core functionality behind Redux, is one of such things for me. That's why 'tis my favourite.

Having said that, do you have any GitHub Gist(s) which you would call your favourite, or which blew your mind, or which you simply like for some reason?