This is a sort of extension to the extremely lacklustre packaging ecosystem of Debian/Ubuntu, sort of a variant on the Arch Linux PKGBUILD/AUR system. Back when I used Debian-based distributions on my personal devices, I used this to supplement my system for the dozens of pieces of important software that were either missing from the official repos or were woefully out of date.
However I no longer use it because I can just use Arch instead and everything works better. The code may still be useful as reference.