anchor.diff:  
     pykka = buildPythonPackage rec {
       name = "pykka-${version}";
  -  
  +
       version = "1.1.0";
  -  
  +
       src = fetchgit {
         url = "https://github.com/jodal/pykka.git";
         rev = "refs/tags/v${version}";
         sha256 = "0w6bcaqkzwmd9habszlgjkp3kkhkna08s9aivnmna5hddsghfqmz";
       };
  -  
  +
       # python zip complains about old timestamps
       preConfigure = ''
         find -print0 | xargs -0 touch
       '';
  -  
  +
       # There are no tests
       doCheck = false;
  -  
  +
       meta = {
         homepage = http://www.pykka.org;
         description = "A Python implementation of the actor model";
  
positive.code: 
    pyspotify = buildPythonPackage rec {
      name = "pyspotify-${version}";
    
      version = "1.11";
    
      src = fetchurl {
        url = "https://github.com/mopidy/pyspotify/archive/v1.11.tar.gz";
        sha256 = "089ml6pqr3f2d15n70jpzbaqjp5pjgqlyv4algkxw92xscjw2izg";
      };
    
      buildInputs = [ pkgs.libspotify ]
        ++ stdenv.lib.optional stdenv.isDarwin pkgs.install_name_tool;
    
      # python zip complains about old timestamps
      preConfigure = ''
        find -print0 | xargs -0 touch
  
negative.code:       md5 = "967a04fcb2143b31b279c3013a778a2b";
      };
  
      buildInputs = [
        docutils
        virtualenv
        webtest
        zope_component
        zope_interface
      ] ++ optional isPy26 unittest2;
  
      propagatedBuildInputs = [
  