anchor.diff:      optionals
       optionalString;
   
  -  version = "4.2.1";
  +  version = "5.0.0";
   
     tarballUrls = version: [
       "mirror://gnu/gawk/gawk-${version}.tar.xz"
  
positive.code:     srcVerification = fetchurl rec {
        inherit (src) outputHashAlgo;
        failEarly = true;
        urls = tarballUrls "4.2.1";
        outputHash = "d1119785e746d46a8209d28b2de404a57f983aa48670f4e225531d3bdc175551";
        pgpsigUrls = map (n: "${n}.sig") urls;
        pgpKeyFingerprint = "D196 7C63 7887 1317 7D86  1ED7 DF59 7815 937E C0D2";
      };
    };
  
  
negative.code:   src = fetchurl {
      urls = tarballUrls version;
      hashOutput = false;
      sha256 = "50f091ed0eb485ad87dbb620d773a3e2c31a27f75f5e008f7bf065055f024406";
    };
  
    # Small build doesn't need floating point with gmp / mpfr
  