anchor.diff:    });
   
     tweepy = buildPythonPackage (rec {
  -    name = "tweepy-1.11";
  +    name = "tweepy-1.12";
   
       src = fetchurl {
         url = "http://pypi.python.org/packages/source/t/tweepy/${name}.tar.gz";
  -      sha256 = "2b9fa225e9254e2cbbb01e59c6e92d9c42e5d41d97e8c74dee93eb09babffde5";
  +      sha256 = "66d728527ab3d5f5e4d6725654783f99169172678105f609d14353f6626c1315";
       };
   
       doCheck = false;
  
positive.code: 
  
    alot = buildPythonPackage rec {
      rev = "5ed59825ffaeaacea90ea10be4b932c60428ed8e";
      name = "alot-0.3.3_${rev}";
  
      src = fetchurl {
        url = "https://github.com/pazz/alot/tarball/${rev}";
        name = "${name}.tar.bz";
        sha256 = "1b724d47bf766ba3ca7cb6d27c7bb597dbc67dcae1347c5a0f01f80c2246ca07";
      };
  
      doCheck = false;
  
negative.code: 
  
    httplib2 = buildPythonPackage rec {
      name = "httplib2-0.7.7";
  
      src = fetchurl {
        url = "http://httplib2.googlecode.com/files/${name}.tar.gz";
        sha256 = "2e2ce18092c32d1ec54f8a447e14e33585e30f240b883bfeeca65f12b3bcfaf6";
      };
  
      doCheck = false; # doesn't have a test
  