anchor.diff:  { stdenv
   , runCommand
   , fetchFromGitHub
  -, libpulseaudio
   , pulseaudio
   , pkgconfig
   , ffmpeg_4
  
positive.code:   ];
  
    buildInputs = [
      libpulseaudio
      pulseaudio
      ffmpeg_4
      libtool
  
negative.code:     for so in $out/lib/pulse-${pulseaudio.version}/modules/*.so; do
        orig_rpath=$(patchelf --print-rpath "$so")
        patchelf \
          --set-rpath "${lib.getLib ffmpeg_4}/lib:$out/lib/pulse-${pulseaudio.version}/modules:$orig_rpath" \
          "$so"
      done
    '';
  