anchor.diff:      and out-of-tree mod packages (mod.nix).
   */
   { lib, makeSetupHook, curl, unzip, dos2unix, pkg-config, makeWrapper
  -, lua, mono, dotnetPackages, python2
  +, lua, mono, dotnetPackages, python3
   , libGL, freetype, openal, SDL2
   , zenity
   }:
  
positive.code: with lib;
  
  let
    path = makeBinPath ([ mono python2 ] ++ optional (zenity != null) zenity);
    rpath = makeLibraryPath [ lua freetype openal SDL2 ];
    mkdirp = makeSetupHook { } ./mkdirp.sh;
  
  
negative.code:       makeWrapper
        mkdirp
        mono
        python3
      ];
  
      makeFlags = [ "prefix=$(out)" ];
  