anchor.diff:  
     semantic = buildPythonPackage rec {
       name = "semantic-1.0.3";
  -    
  +
       disabled = isPy3k;
   
       propagatedBuildInputs = [ quantities numpy ];
  
positive.code:   gevent = buildPythonPackage rec {
      name = "gevent-1.0.1";
      disabled = isPy3k;
      
      src = fetchurl {
        url = "https://pypi.python.org/packages/source/g/gevent/${name}.tar.gz";
        sha256 = "0hyzfb0gcx9pm5c2igan8y57hqy2wixrwvdjwsaivxsqs0ay49s6";
  
negative.code:     };
  
      buildInputs = [ unittest2 ];
  
      doCheck = !isPyPy;
  
      meta = {
  