anchor.diff:  
   
     mccabe = buildPythonPackage (rec {
  -    name = "mccabe-0.2";
  +    name = "mccabe-0.2.1";
   
       src = fetchurl {
         url = "http://pypi.python.org/packages/source/m/mccabe/${name}.tar.gz";
  -      md5 = "c1012c7c24081471f45aab864d4e3805";
  +      md5 = "5a3f3fa6a4bad126c88aaaa7dab682f5";
       };
   
       buildInputs = [ ];
  
positive.code: 
    pep8 = buildPythonPackage rec {
      name = "pep8-${version}";
      version = "1.4.5";
  
      src = fetchurl {
        url = "http://pypi.python.org/packages/source/p/pep8/${name}.tar.gz";
        md5 = "055dbd22ac5669232fdba752612e9686";
      };
  
      #======================================================================
  
negative.code:   };
  
    pyflakes = buildPythonPackage rec {
      name = "pyflakes-0.7.3";
  
      src = fetchurl {
        url = "http://pypi.python.org/packages/source/p/pyflakes/${name}.tar.gz";
        md5 = "ec94ac11cb110e6e72cca23c104b66b1";
      };
  
      buildInputs = [ unittest2 ];
  