anchor.diff:        system.nixos.revision = nixpkgs.rev or nixpkgs.shortRev;
       };
   
  +  makeModules = module: rest: [ configuration versionModule module rest ];
   
     makeIso =
       { module, type, system, ... }:
  
positive.code: 
        config = (import lib/eval-config.nix {
          inherit system;
          modules = [ configuration module versionModule ];
        }).config;
  
        tarball = config.system.build.tarball;
  
negative.code: 
      hydraJob ((import lib/eval-config.nix {
        inherit system;
        modules = makeModules module {
          isoImage.isoBaseName = "nixos-${type}";
        };
      }).config.system.build.isoImage);
  
  
  