anchor.diff:      };
     });
   
  +  lxml_3_5 = buildPythonPackage ( rec {
  +    name = "lxml-3.5.0";
  +
  +    src = pkgs.fetchurl {
  +      url = "mirror://pypi/l/lxml/${name}.tar.gz";
  +      sha256 = "0y7m2s8ci6q642zl85y5axkj8z827l0vhjl532acb75hlkir77rl";
  +    };
  +
  +    buildInputs = with self; [ pkgs.libxml2 pkgs.libxslt ];
  +
  +    meta = {
  +      description = "Pythonic binding for the libxml2 and libxslt libraries";
  +      homepage = http://lxml.de;
  +      license = licenses.bsd3;
  +    };
  +  });
   
     python_magic = buildPythonPackage rec {
       name = "python-magic-0.4.10";
  
positive.code:   };
  
  
    pyasn1 = buildPythonPackage ({
      name = "pyasn1-0.1.8";
  
      src = pkgs.fetchurl {
        url = "mirror://sourceforge/pyasn1/0.1.8/pyasn1-0.1.8.tar.gz";
        sha256 = "0iw31d9l0zwx35szkzq72hiw002wnqrlrsi9dpbrfngcl1ybwcsx";
      };
  
      meta = {
  
negative.code: 
    certifi = buildPythonPackage rec {
      name = "certifi-${version}";
      version = "2015.11.20.1";
  
      src = pkgs.fetchurl {
        url = "mirror://pypi/c/certifi/${name}.tar.gz";
        sha256 = "05lgwf9rz1kn465azy2bpb3zmpnsn9gkypbhnjlclchv98ssgc1h";
      };
  
      meta = {
  