anchor.diff:  { stdenv, fetchurl, pythonPackages, gettext, pyqt4
  -, pkgconfig, libdiscid, libofa, ffmpeg, acoustidFingerprinter
  +, pkgconfig, libdiscid, libofa, ffmpeg, chromaprint
   }:
   
   pythonPackages.buildPythonPackage rec {
  
positive.code: 
    doCheck = false;
  
    meta = {
      homepage = "http://musicbrainz.org/doc/MusicBrainz_Picard";
      description = "The official MusicBrainz tagger";
      license = stdenv.lib.licenses.gpl2;
    };
  }
  
negative.code: 
    src = fetchurl {
      url = "http://ftp.musicbrainz.org/pub/musicbrainz/picard/${name}.tar.gz";
      sha256 = "0sbsf8hzxhxcnnjqvsd6mc23lmk7w33nln0f3w72f89mjgs6pxm6";
    };
  
    postPatch = let
      discid = "${libdiscid}/lib/libdiscid.so.0";
      fpr = "${chromaprint}/bin/fpcalc";
    in ''
      substituteInPlace picard/disc.py --replace libdiscid.so.0 ${discid}
      substituteInPlace picard/const.py \
          --replace "FPCALC_NAMES = [" "FPCALC_NAMES = ['${fpr}',"
    '';
  
    buildInputs = [
  