anchor.diff:  
     nativeBuildInputs = [
       which
  +    perl
       python3
       ruby
     ];
  
positive.code:   buildPhase = ''
      runHook preBuild
      mkdir -p $out/lib
      ./build.sh -qt5 -prefix $out/lib -j$NIX_BUILD_CORES
      runHook postBuild
    '';
  
  
negative.code: { lib, mkDerivation, fetchFromGitHub
  , python3, ruby, qtbase, qtmultimedia, qttools, qtxmlpatterns
  , which, perl
  }:
  
  mkDerivation rec {
    pname = "klayout";
    version = "0.27.8";
  
    src = fetchFromGitHub {
      owner = "KLayout";
      repo = "klayout";
      rev = "v${version}";
      hash = "sha256-t/nd7m8XpB026q/kyH16rKkw3qza19ISalB0Juzx4NU=";
    };
  
    postPatch = ''
  