anchor.diff:  
     certifi = buildPythonPackage rec {
       name = "certifi-${version}";
  -    version = "2015.9.6.2";
  +    version = "2015.11.20.1";
   
       src = pkgs.fetchurl {
         url = "mirror://pypi/c/certifi/${name}.tar.gz";
  -      sha256 = "19mfly763c6bzya9dwm6qgc48z4x3gk6ldl6fprdncqhklnjnfnw";
  +      sha256 = "05lgwf9rz1kn465azy2bpb3zmpnsn9gkypbhnjlclchv98ssgc1h";
       };
   
       meta = {
  
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: 
    lxml = buildPythonPackage ( rec {
      name = "lxml-3.4.4";
  
      src = pkgs.fetchurl {
        url = "mirror://pypi/l/lxml/${name}.tar.gz";
  