anchor.diff:  , enableDiscogs        ? true
   , enableEmbyupdate     ? true
   , enableFetchart       ? true
  +, enableGmusic         ? true
   , enableKeyfinder      ? true, keyfinder-cli ? null
  +, enableKodiupdate     ? true
   , enableLastfm         ? true
   , enableMpd            ? true
   , enableReplaygain     ? true, bs1770gain ? null
  
positive.code:     discogs = enableDiscogs;
      embyupdate = enableEmbyupdate;
      fetchart = enableFetchart;
      keyfinder = enableKeyfinder;
      lastgenre = enableLastfm;
      lastimport = enableLastfm;
      mpdstats = enableMpd;
  
negative.code:   ] ++ optional enableAcoustid     pythonPackages.pyacoustid
      ++ optional (enableFetchart
                || enableEmbyupdate
                || enableKodiupdate
                || enableAcousticbrainz)
                                     pythonPackages.requests
      ++ optional enableConvert      ffmpeg
      ++ optional enableDiscogs      pythonPackages.discogs_client
      ++ optional enableGmusic       pythonPackages.gmusicapi
      ++ optional enableKeyfinder    keyfinder-cli
      ++ optional enableLastfm       pythonPackages.pylast
      ++ optional enableMpd          pythonPackages.mpd2
      ++ optional enableThumbnails   pythonPackages.pyxdg
      ++ optional enableWeb          pythonPackages.flask
      ++ optional enableAlternatives (import ./alternatives-plugin.nix {
  