anchor.diff:  
     nativeBuildInputs = [
       which
  +    perl
       python3
       ruby
     ];
  
positive.code: { lib, mkDerivation, fetchFromGitHub, fetchpatch
  , python3, ruby, qtbase, qtmultimedia, qttools, qtxmlpatterns
  , which, perl, makeWrapper
  }:
  
  mkDerivation rec {
    pname = "klayout";
    version = "0.27.3";
  
    src = fetchFromGitHub {
      owner = "KLayout";
      repo = "klayout";
      rev = "v${version}";
      sha256 = "sha256-6g/QoR16rhUfxhH4JxL6EERcoPVG/6MOxUlo6K/WoE0=";
    };
  
    postPatch = ''
  
negative.code:   buildPhase = ''
      runHook preBuild
      mkdir -p $out/lib
      ./build.sh -qt5 -prefix $out/lib -option -j$NIX_BUILD_CORES
      runHook postBuild
    '';
  
  