anchor.diff: -{ lib, stdenv, buildPythonPackage, isPyPy, fetchPypi, libffi, pycparser, pytest }:
  +{ lib, stdenv, buildPythonPackage, isPyPy, fetchPypi, libffi, pycparser, pytestCheckHook }:
   
   if isPyPy then null else buildPythonPackage rec {
     pname = "cffi";
  
positive.code:     "-Wno-unused-command-line-argument -Wno-unreachable-code";
  
    doCheck = !stdenv.hostPlatform.isMusl && !stdenv.isDarwin; # TODO: Investigate
    checkPhase = ''
      py.test -k "not test_char_pointer_conversion"
    '';
  
    meta = with lib; {
      maintainers = with maintainers; [ domenkozar lnl7 ];
  
negative.code:   outputs = [ "out" "dev" ];
  
    propagatedBuildInputs = [ libffi pycparser ];
  
    # On Darwin, the cffi tests want to hit libm a lot, and look for it in a global
    # impure search path. It's obnoxious how much repetition there is, and how difficult
  