anchor.diff:  { stdenv
   , buildPythonPackage
   , fetchPyPi
  +, lib
   
   , libffi
   , pycparser
  
positive.code: 
    doCheck = false;
  
    meta = with stdenv.lib; {
      description = "Foreign Function Interface for Python calling C code";
      homepage = http://cffi.readthedocs.org/;
      license = licenses.mit;
  
negative.code: }:
  
  let
    inherit (lib)
      optionals;
  
    version = "1.10.0";
  