anchor.diff:    src = fetchurl {
       urls = tarballUrls version;
       hashOutput = false;
  -    sha256 = "fd22fc5ed02b42c88fa0efc6d5de3face8dfb5e253bf97e632573413969bc900";
  +    sha256 = "039ee45b61d95e5003e7e8376f9080001b4066ff357bde271b7faace53b9d804";
     };
   
     nativeBuildInputs = [
  
positive.code:     "mirror://gnu/bison/bison-${version}.tar.xz"
    ];
  
    version = "3.3.1";
  in
  stdenv.mkDerivation (rec {
    name = "bison-${version}";
  
negative.code:   passthru = {
      srcVerification = fetchurl rec {
        failEarly = true;
        urls = tarballUrls "3.3.2";
        inherit (src) outputHashAlgo;
        outputHash = "039ee45b61d95e5003e7e8376f9080001b4066ff357bde271b7faace53b9d804";
        fullOpts = {
          pgpsigUrls = map (n: "${n}.sig") urls;
          pgpKeyFingerprint = "7DF8 4374 B1EE 1F97 64BB  E25D 0DDC AA32 78D5 264E";
  