anchor.diff:    validTweaks = [ "nord" "dracula" "black" "rimless" "normal" ];
   
     unknownTweaks = lib.subtractLists validTweaks tweaks;
  -  illegalMix = !(lib.elem "nord" tweaks) && !(lib.elem "dracula" tweaks);
  +  illegalMix = (lib.elem "nord" tweaks) && (lib.elem "dracula" tweaks);
   
  -  assertIllegal = lib.assertMsg illegalMix ''
  +  assertIllegal = lib.assertMsg (!illegalMix) ''
       Tweaks "nord" and "dracula" cannot be mixed. Tweaks: ${toString tweaks}
     '';
   
  
positive.code: 
  stdenvNoCC.mkDerivation rec {
    pname = "catppuccin-gtk";
    version = "unstable-2022-08-01";
  
    src = fetchFromGitHub {
      repo = "gtk";
      owner = "catppuccin";
      rev = "87a79fd2bf07accc694455df30a32a82b1b31f4f";
      sha256 = "sha256-dKHTQva0BYkO6VPNfY/pzRn/V1ghX+tYqbnM9hTAMeE=";
    };
  
    nativeBuildInputs = [ gtk3 sassc which ];
  
    buildInputs = [ gnome-themes-extra ];
  
  
negative.code: , gnome-themes-extra
  , gtk-engine-murrine
  , sassc
  , tweaks ? [ ]
  , size ? "standard"
  }:
  