anchor.diff:      owner = "sagemath";
       repo = "zn_poly";
       rev = version;
  -    sha256 = "0ra5vy585bqq7g3317iw6fp44iqgqvds3j0l1va6mswimypq4vxb";
  +    hash = "sha256-QBItcrrpOGj22/ShTDdfZjm63bGW2xY4c71R1q8abPE=";
     };
   
     buildInputs = [
  
positive.code: , fetchFromGitLab
  , fetchpatch
  , gmp
  , python2
  , tune ? false # tune to hardware, impure
  }:
  
  stdenv.mkDerivation rec {
    version = "0.9.1";
    pname = "zn_poly";
  
    # sage has picked up the maintenance (bug fixes and building, not development)
  
negative.code: 
    configureFlags = lib.optionals (!tune) [
      "--disable-tuning"
    ];
  
    # `make install` fails to install some header files and the lib file.
  