anchor.diff:    inherit (stdenv.lib)
       attrNames
       concatMapStrings
  +    concatStringsSep
       elem
  +    filterAttrs
  +    id
       makeSearchPath
       optional
       optionals
  
positive.code:   , flac ? null
    , mp3val ? null
  , enableBpd ? false
    , gst-python_0 ? null
    , gst-plugins-base_0 ? null
  , enableDiscogs ? true
  , enableEchonest ? true
  , enableEmbyupdate ? true
  , enableFetchart ? true
  , enableLastfm ? true
  , enableMpd ? true
  
negative.code: , writeScript
  
  , python
  , python2Packages
  , imagemagick
  
  , enableAcousticbrainz ? true
  