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