anchor.diff:      poppler
       popt
       potrace
  -    python2Env
  +    python3Env
       zlib
     ] ++ stdenv.lib.optionals (!stdenv.isDarwin) [
       gtkspell2
  
positive.code: , poppler
  , popt
  , potrace
  , python2
  , wrapGAppsHook
  , zlib
  }:
  let
    python2Env = python2.withPackages
      (ps: with ps; [
        numpy
        lxml
  
negative.code:     # Python is used at run-time to execute scripts, e.g., those from
      # the "Effects" menu.
      substituteInPlace src/extension/implementation/script.cpp \
        --replace '"python-interpreter", "python"' '"python-interpreter", "${python3Env}/bin/python"'
    '';
  
    nativeBuildInputs = [
      pkg-config
      cmake
      makeWrapper
      python3Env
      wrapGAppsHook
    ] ++ (with perlPackages; [
      perl
  