anchor.diff:  
     facebook-sdk = buildPythonPackage rec {
       name = "facebook-sdk-0.4.0";
  +    
  +    disabled = isPy3k;
   
       src = fetchurl {
         url = "https://pypi.python.org/packages/source/f/facebook-sdk/facebook-sdk-0.4.0.tar.gz";
  
positive.code: 
    semantic = buildPythonPackage rec {
      name = "semantic-1.0.3";
  
      propagatedBuildInputs = with pythonPackages; [ quantities numpy ];
  
      src = fetchurl {
        url = "https://pypi.python.org/packages/source/s/semantic/semantic-1.0.3.tar.gz";
  
negative.code:     };
  
       # test fail (timezone test fail)
       doCheck = false;
  
      meta = with pkgs.stdenv.lib; {
        description = "Tzinfo object for the local timezone.";
  