anchor.diff:      ++ lib.optional enableCheck         beetsExternalPlugins.check
       ++ lib.optional enableConvert       ffmpeg
       ++ lib.optional enableDiscogs       pythonPackages.discogs_client
  -    ++ lib.optional enableGmusic        pythonPackages.gmusicapi
       ++ lib.optional enableKeyfinder     keyfinder-cli
       ++ lib.optional enableLastfm        pythonPackages.pylast
       ++ lib.optional enableMpd           pythonPackages.mpd2
  
positive.code:     echo echo completion tests passed > test/rsrc/test_completion.sh
  
      sed -i -e 's/len(mf.images)/0/' test/test_zero.py
    '';
  
    postInstall = ''
  
negative.code: , enableDiscogs          ? true
  , enableEmbyupdate       ? true
  , enableFetchart         ? true
  , enableKeyfinder        ? true, keyfinder-cli
  , enableKodiupdate       ? true
  , enableLastfm           ? true
  