I’m one of the organizers of Hack N Roll and personally know the guy who built this.

He says that the code on Github is actually broken but he forgot in what way.. I still think it’s pretty cool though

I tried running this on a Mac but got an error. Assumed it was because of some sed version difference. Perhaps the code on Github is just broken.

That's probably because you used BSD sed. Running it on my BSD sed also gives an error, presumably because it thinks the `}` is a part of the label in `binput}`.

However it works fine in GNU sed, and now that you mention it, GNU sed's extensions were not used, like the `-z` flag to slurp all input in one "line" to avoid `:input;$!{N;binput}`.

On macOS: install gnu-sed via Homebrew.

It works with the GNU sed that ships with GitBash on Windows.