final: prev: rec {
  # keep sources this first
  sources = prev.callPackage (import ./sources.nix) { };
  # then, call packages with `final.callPackage`
  go-fold-if-err-nil = final.callPackage ./go-fold-if-err-nil.nix { };
  security-wordlists = final.callPackage (import "${sources.wordlists.src}/pkgs/tools/security/wordlists/default.nix") { };
}