anchor.diff:    dontUseCmakeBuildDir = true;
   
     cmakeFlags = [
  -    "-DEIGEN3_INCLUDE_DIR=${eigen}/include/eigen3"
  +    "-DBoost_INCLUDE_DIR=${lib.getDev boost}/include"
  +    "-DEIGEN3_INCLUDE_DIR=${lib.getDev eigen}/include/eigen3"
       "-DBUILD_TESTING=on"
     ] ++ lib.optionals (python.isPy3k && !stdenv.cc.isClang) [
       "-DPYBIND11_CXX_STANDARD=-std=c++17"
  
positive.code: , buildPythonPackage
  , fetchFromGitHub
  , cmake
  , eigen
  , python
  , catch
  
negative.code: 
  buildPythonPackage rec {
    pname = "pybind11";
    version = "2.8.1";
  
    src = fetchFromGitHub {
      owner = "pybind";
      repo = pname;
      rev = "v${version}";
      sha256 = "sha256-Gk4ZN/g6SRWFm0ALCvyald/9zq3wBd48mGdqdGCeGYI=";
    };
  
    nativeBuildInputs = [ cmake ];
  