anchor.diff:  
         splashImage = mkOption {
           default =
  -          if config.boot.loader.grub.version == 1
  +          if cfg.version == 1
             then pkgs.fetchurl {
               url = http://www.gnome-look.org/CONTENT/content-files/36909-soft-tux.xpm.gz;
               sha256 = "14kqdx2lfqvh40h6fjjzqgff1mwk74dmbjvmqphi6azzra7z8d59";
  
positive.code:     # set at once.
      system.boot.loader.id = "grub";
  
      environment.systemPackages = mkIf config.boot.loader.grub.enable [ grub ];
  
    };
  
  
negative.code: 
    cfg = config.boot.loader.grub;
  
    realGrub = if cfg.version == 1 then pkgs.grub else pkgs.grub2;
  
    grub =
      # Don't include GRUB if we're only generating a GRUB menu (e.g.,
      # in EC2 instances).
      if cfg.devices == ["nodev"]
      then null
      else realGrub;
  
    f = x: if x == null then "" else "" + x;
  
  