anchor.diff:      sha256 = "sha256-ZHplYEG97foy/unOdSokFFkDl4LK5TI4kypHSLpcCM4=";
     };
   
  +  patches = [
  +    (fetchpatch {
  +      # setuptools 61 compat
  +      url = "https://github.com/symengine/symengine.py/commit/987e665e71cf92d1b021d7d573a1b9733408eecf.patch";
  +      hash = "sha256-2QbNdw/lKYRIRpOU5BiwF2kK+5Lh2j/Q82MKUIvl0+c=";
  +    })
  +  ];
  +
     postConfigure = ''
       substituteInPlace setup.py \
         --replace "\"cmake\"" "\"${cmake}/bin/cmake\"" \
         --replace "'cython>=0.29.24'" "'cython'"
  -
  -    substituteInPlace cmake/FindCython.cmake \
  -      --replace "SET(CYTHON_BIN cython" "SET(CYTHON_BIN ${cython}/bin/cython"
     '';
   
     nativeBuildUnputs = [ cmake ];
  
positive.code: buildPythonPackage rec {
    pname = "symengine";
    version = "0.9.2";
  
    src = fetchFromGitHub {
      owner = "symengine";
  
negative.code: { lib
  , buildPythonPackage
  , fetchpatch
  , fetchFromGitHub
  , cython
  , cmake
  