anchor.diff:  { lib
   , stdenv
   , fetchFromGitLab
  -, docbook_xsl
  +, docbook-xsl-nons
   , gtk-doc
   , meson
   , ninja
  
positive.code:   };
  
    nativeBuildInputs = [
      docbook_xsl
      gtk-doc
      meson
      ninja
  
negative.code:   version = "unstable-2021-05-01";
  
    outputs = [ "out" "dev" "devdoc" ];
    outputBin = "dev";
  
    src = fetchFromGitLab {
      domain = "gitlab.gnome.org";
  