anchor.diff:  
     propagatedBuildInputs = optionals (!isPyPy) [
       greenlet
  +  ] ++ [
  +    dnspython
  +    idna
     ];
   
  -  prePatch = ''
  -    rm -rf libev
  -  '';
  +  NIX_CFLAGS_COMPILE = [
  +    "-I${greenlet}/include/${python.executable}${if isPy3 then "m" else ""}"
  +  ];
  +
  +  buildDirCheck = false;  # FIXME
   
     meta = with lib; {
       description = "Coroutine-based networking library";
  
positive.code:   inherit (lib)
      optionals;
  
    version = "1.2.2";
  in
  buildPythonPackage rec {
    name = "gevent-${version}";
  
    src = fetchPyPi {
      package = "gevent";
      inherit version;
      sha256 = "4791c8ae9c57d6f153354736e1ccab1e2baf6c8d9ae5a77a9ac90f41e2966b2d";
    };
  
    buildInputs = [
      libev
  
negative.code: { stdenv
  , buildPythonPackage
  , cython
  , fetchFromGitHub
  #, fetchPyPi
  , isPy3
  , isPyPy
  , lib
  , python
  
  , dnspython
  , greenlet
  , idna
  , libev
  }:
  
  