anchor.diff:  
     postFixup = "gtk-update-icon-cache $out/share/icons/elementary";
   
  +  passthru = {
  +    updateScript = nix-update-script {
  +      attrPath = "pantheon.${pname}";
  +    };
  +  };
  +
     meta = with lib; {
       description = "Named, vector icons for elementary OS";
       longDescription = ''
  
positive.code: { lib, stdenv
  , fetchFromGitHub
  , nix-update-script
  , pantheon
  
negative.code:     owner = "elementary";
      repo = repoName;
      rev = version;
      sha256 = "sha256-WR4HV0nJKj0WeSFHXLK64O0LhX8myAJE4w0aztyhPn4=";
    };
  
    nativeBuildInputs = [
  