anchor.diff:        config = (import lib/eval-config.nix {
           inherit system;
           modules =
  -          [ ./modules/virtualisation/virtualbox-image.nix
  +          [ versionModule
  +            ./modules/virtualisation/virtualbox-image.nix
               ./modules/installer/cd-dvd/channel.nix
               ./modules/profiles/demo.nix
             ];
  
positive.code: 
      let
  
        versionModule =
          { system.nixosVersionSuffix = lib.optionalString (!officialRelease) versionSuffix;
            isoImage.isoBaseName = "nixos-${type}";
          };
  
        config = (import lib/eval-config.nix {
          inherit system;
          modules = [ module versionModule ];
        }).config;
  
        iso = config.system.build.isoImage;
  
negative.code:       }).config;
  
        tarball = config.system.build.tarball;
  
      in
        tarball //
          { meta = {
  