anchor.diff:  buildPythonPackage rec {
     # also bump cryptography_vectors
     pname = "cryptography";
  -  version = "2.4.2";
  +  version = "2.5";
   
     src = fetchPypi {
       inherit pname version;
  -    sha256 = "1pc60dksi9w9mshl6cvn7gdjazbp3pmydy3qp9wgy5wzd8n0b9h5";
  +    sha256 = "00c4d7gvsymlaw0r13zrm32dcnarmpayjyrh65yymlmr6mrbcij9";
     };
   
     outputs = [ "out" "dev" ];
  
positive.code: , openssl
  , cryptography_vectors
  , darwin
  , idna
  , asn1crypto
  , packaging
  , six
  
negative.code:   buildInputs = [ openssl cryptography_vectors ]
               ++ stdenv.lib.optional stdenv.isDarwin darwin.apple_sdk.frameworks.Security;
    propagatedBuildInputs = [
      asn1crypto
      packaging
      six
  