The code seems to be on Sourceforge but the files I looked at were short and didn't seem to be able to handle 509 different things. So I think I looked in the wrong files. Or it's not in the repo?
[edit] it is written in the 'Fusion Language' https://github.com/fusionlanguage/fut (and not https://gaelduval.com/introducing-fusion-the-ultimate-progra... !) - there's a playground at http://fusion-lang.org/ . I'd never heard of it before but seems a bit like Haxe perhaps?