anchor.diff:  
   stdenv.mkDerivation rec {
     name = "mkvtoolnix-${version}";
  -  version = "28.2.0";
  +  version = "31.0.0";
   
     src = fetchFromGitLab {
       owner  = "mbunkus";
       repo   = "mkvtoolnix";
       rev    = "release-${version}";
  -    sha256 = "162qj5z9wzm63im6jnd0n95ggzdk6fzq5bxgrr0l3y82ahfb7qwa";
  +    sha256 = "1fml374ivzzmac0ixhngj4bdxszcaw5yxdmacpn6ia7pdyvpf5lh";
     };
   
     nativeBuildInputs = [
  
positive.code: { stdenv, fetchFromGitLab, pkgconfig, autoconf, automake, libiconv
  , drake, ruby, docbook_xsl, file, xdg_utils, gettext, expat, boost
  , libebml, zlib, libmatroska, libogg, libvorbis, flac, libxslt, cmark
  , withGUI ? true
    , qtbase ? null
    , qtmultimedia ? null
  
negative.code:   ];
  
    buildInputs = [
      expat file xdg_utils boost libebml zlib fmt
      libmatroska libogg libvorbis flac cmark
    ] ++ optional  stdenv.isDarwin libiconv
      ++ optionals withGUI [ qtbase qtmultimedia ];
  