anchor.diff:  , buildPythonPackage
   , fetchFromGitHub
   , cffi
  -, pkgs
  +, libspotify
   }:
   
   buildPythonPackage rec {
  
positive.code:   };
  
    propagatedBuildInputs = [ cffi ];
    buildInputs = [ pkgs.libspotify ];
  
    # python zip complains about old timestamps
    preConfigure = ''
  
negative.code:     find "$out" -name _spotify.so -exec \
          install_name_tool -change \
          @loader_path/../Frameworks/libspotify.framework/libspotify \
          ${libspotify}/lib/libspotify.dylib \
          {} \;
    '';
  
  