anchor.diff:    twisted = buildPythonPackage rec {
       # NOTE: When updating please check if new versions still cause issues
       # to packages like carbon (http://stackoverflow.com/questions/19894708/cant-start-carbon-12-04-python-error-importerror-cannot-import-name-daem)
  -
  +    disabled = isPy3k;
  + 
       name = "Twisted-11.1.0";
       src = fetchurl {
         url = "https://pypi.python.org/packages/source/T/Twisted/${name}.tar.bz2";
  
positive.code: 
  
    pycurl = buildPythonPackage (rec {
      name = "pycurl-7.19.0";
  
      src = fetchurl {
        url = "http://pycurl.sourceforge.net/download/${name}.tar.gz";
        sha256 = "0hh6icdbp7svcq0p57zf520ifzhn7jw64x07k99j7h57qpy2sy7b";
      };
  
      buildInputs = [ pkgs.curl ];
  
negative.code: 
    urlgrabber =  buildPythonPackage rec {
      name = "urlgrabber-3.9.1";
      disabled = isPy3k;
  
      src = fetchurl {
        url = "http://urlgrabber.baseurl.org/download/${name}.tar.gz";
  