anchor.diff:      mpdstats = enableMpd;
       mpdupdate = enableMpd;
       replaygain = enableReplaygain;
  +    sonosupdate = enableSonosUpdate;
       thumbnails = enableThumbnails;
       web = enableWeb;
     };
  
positive.code: assert enableLastfm      -> pythonPackages.pylast         != null;
  assert enableMpd         -> pythonPackages.mpd2           != null;
  assert enableReplaygain  -> bs1770gain                    != null;
  assert enableThumbnails  -> pythonPackages.pyxdg          != null;
  assert enableWeb         -> pythonPackages.flask          != null;
  
  
negative.code: , enableLastfm         ? true
  , enableMpd            ? true
  , enableReplaygain     ? true, bs1770gain ? null
  , enableSonosUpdate    ? true
  , enableThumbnails     ? true
  , enableWeb            ? true
  
  