Wallpaper carousel of predefined wallpapers using nix

This is really badly written stuff that I put together for my own use.

What it does:

If you have a list of urls, local files, and local directories that you'd like to use as wallpaper then adapt this code for your use. I made this because I feel that downloading wallpaper is a problem that might be better relegated to nix so my only work is to save urls.

How it works: It downloads wallpapers from urls and prints their hash if youd like to mention hash. Doing so prevents redownload. Not doing so means you'll have to change the FOD hash.

This is badly written code with parameters all over the place but it works for me and I'm pasting here in the hope it works for someone else.