anchor.diff:  
   
     zope_sqlalchemy = buildPythonPackage rec {
  -    name = "zope.sqlalchemy-0.7.2";
  +    name = "zope.sqlalchemy-0.7.3";
   
       src = fetchurl {
         url = "http://pypi.python.org/packages/source/z/zope.sqlalchemy/${name}.zip";
  -      md5 = "b654e5d144ed141e13b42591a21a4868";
  +      md5 = "8b317b41244fc2e67f2f286890ba59a0";
       };
   
       buildInputs = [ pkgs.unzip sqlalchemy zope_testing zope_interface setuptools ];
  
positive.code: 
  
    colander = buildPythonPackage rec {
      name = "colander-1.0a5";
  
      src = fetchurl {
        url = "http://pypi.python.org/packages/source/c/colander/${name}.tar.gz";
        md5 = "569dea523561f5d94338ef9d9a98d249";
      };
  
      propagatedBuildInputs = [ pythonPackages.translationstring ];
  
negative.code: 
  
    turses = buildPythonPackage (rec {
      name = "turses-0.2.19";
  
      src = fetchurl {
        url = "http://pypi.python.org/packages/source/t/turses/${name}.tar.gz";
        sha256 = "1g58ahxpaf0wqn6gg5a2n3fkvc3vbx6jpylwqncxnl16qcczmjxn";
      };
  
      propagatedBuildInputs = [ oauth2 urwid tweepy ] ++ optional isPy26 argparse;
  