anchor.diff:  
       buildInputs = [ pkgs.openssl self.pretend self.cryptography_vectors
                       self.iso8601 self.pyasn1 self.pytest ];
  -    propagatedBuildInputs = [ self.six self.cffi  ];
  +    propagatedBuildInputs = [ self.six ] ++ optional (!isPyPy) self.cffi; 
     };
   
     cryptography_vectors = buildPythonPackage rec {
  
positive.code:     };
    };
  
    MySQL_python = buildPythonPackage {
      name = "MySQL-python-1.2.3";
  
      disabled = isPy3k;
  
  
negative.code:       sha256 = "00jaf7x1ji9y46fbkww2sg6r6almrqfsprydz3q2swr4jrnrsx9x";
      };
  
      prePatch = ''
        substituteInPlace setup.py \
          --replace "httplib2==0.8" "httplib2" \
          --replace "iso8601==0.1.4" "iso8601"
  