anchor.diff:  
     nativeBuildInputs = [ autoreconfHook ];
     buildInputs =
  -    [ pkgconfig perl python libxml2Python libxslt docbook_xml_dtd_43 docbook_xsl
  +    [ pkgconfig perl python3 libxml2Python libxslt docbook_xml_dtd_43 docbook_xsl
         gnome-doc-utils gettext which itstool
       ] ++ stdenv.lib.optional withDblatex dblatex;
   
  
positive.code: { stdenv, fetchurl, autoreconfHook, pkgconfig, perl, python, libxml2Python, libxslt, which
  , docbook_xml_dtd_43, docbook_xsl, gnome-doc-utils, gettext, itstool
  , withDblatex ? false, dblatex
  }:
  
  stdenv.mkDerivation rec {
    name = "gtk-doc-${version}";
    version = "1.28";
  
    src = fetchurl {
      url = "mirror://gnome/sources/gtk-doc/${version}/${name}.tar.xz";
      sha256 = "05apmwibkmn1icx05l8aw241lhymcx01zvk5i499cb150bijj7li";
    };
  
    patches = [
  
negative.code:   # Make six available for binaries, python.withPackages creates a wrapper
    # but scripts are not allowed in shebangs so we link it into sys.path.
    postInstall = ''
      ln -s ${python3.pkgs.six}/${python3.sitePackages}/* $out/share/gtk-doc/python/
    '';
  
    doCheck = false; # requires a lot of stuff
  