anchor.diff:    tarballUrls = base: patch: map (n: "${n}/util-linux-${version base patch}.tar") (baseUrls base);
   
     base = "2.28";
  -  patch = null;
  +  patch = "1";
   in
   
   stdenv.mkDerivation rec {
  
positive.code:   passthru = {
      srcVerification = fetchurl {
        failEarly = true;
        urls = map (n: "${n}.xz") (tarballUrls "2.28" null);
        pgpsigUrls = map (n: "${n}.sign") (tarballUrls "2.28" null);
        pgpsigSha256Urls = map (n: "${n}/sha256sums.asc") (baseUrls "2.28");
        pgpKeyFingerprint = "B0C6 4D14 301C C6EF AEDF  60E4 E4B7 1D5E EC39 C284";
        pgpDecompress = true;
        outputHash = "395847e2a18a2c317170f238892751e73a57104565344f8644090c8b091014bb";
        inherit (src) outputHashAlgo;
      };
    };
  
negative.code:   src = fetchurl {
      urls = map (n: "${n}.xz") (tarballUrls base patch);
      allowHashOutput = false;
      sha256 = "3ece4ea4a34ef786b68f5c415e848390424232abd1ee00f7ee5bddc30657b60f";
    };
  
    nativeBuildInputs = [
  