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