anchor.diff:  
     configureFlags = lib.optionals (!tune) [
       "--disable-tuning"
  -  ];
  -
  -  patches = [
  -    # fix format-security by not passing variables directly to printf
  -    # https://gitlab.com/sagemath/zn_poly/merge_requests/1
  -    (fetchpatch {
  -      name = "format-security.patch";
  -      url = "https://gitlab.com/timokau/zn_poly/commit/1950900a80ec898d342b8bcafa148c8027649766.patch";
  -      sha256 = "1gks9chvsfpc6sg5h3nqqfia4cgvph7jmj9dw67k7dk7kv9y0rk1";
  -    })
     ];
   
     # `make install` fails to install some header files and the lib file.
  
positive.code:   ];
  
    nativeBuildInputs = [
      python2 # needed by ./configure to create the makefile
    ];
  
    # name of library file ("libzn_poly.so")
  
negative.code:     owner = "sagemath";
      repo = "zn_poly";
      rev = version;
      hash = "sha256-QBItcrrpOGj22/ShTDdfZjm63bGW2xY4c71R1q8abPE=";
    };
  
    buildInputs = [
  