anchor.diff:  , fetchPypi
   , buildPythonPackage
   , cython
  -, sphinx
  +, pariSupport ? true, pari # for interfacing with the PARI/GP signal handler
   }:
  +
  +assert pariSupport -> pari != null;
   
   buildPythonPackage rec {
     pname = "cysignals";
  
positive.code:     sha256 = "15nky8siwlc7s8v23vv4m0mnxa1z6jcs2qfr26m2mkw9j9g2na2j";
    };
  
    hardeningDisable = [
      "fortify"
    ];
  
negative.code:     # Make sure cysignals-CSI is in PATH
      export PATH="$out/bin:$PATH"
    '';
  
    buildInputs = lib.optionals pariSupport [
      pari
    ];
  
    propagatedBuildInputs = [
      cython
  