anchor.diff:    src = fetchurl {
       urls = map (n: "${n}.xz") (tarballUrls version);
       hashOutput = false;
  -    sha256 = "f53f5169cb98cfca471ddea30092738c427ba284c5356e01b45dd1ae3b297e0d";
  +    sha256 = "397dc96f51aeeff73d021d3418d3172377b2685f2740ca60525096c070aa3df1";
     };
   
     nativeBuildInputs = [
  
positive.code:     "mirror://kernel/linux/utils/fs/xfs/xfsprogs/xfsprogs-${version}.tar"
    ];
  
    version = "4.17.0";
  in
  stdenv.mkDerivation rec {
    name = "xfsprogs-${version}";
  
negative.code:         outputHash
          outputHashAlgo
          urls;
        failEarly = true;
        fullOpts = {
          pgpDecompress = true;
          pgpsigUrl = map (n: "${n}.sign") (tarballUrls version);
          pgpKeyFingerprints = [
            # Dave Chinner
            "9893 A827 C19F 7D96 164A  38FF ADE8 2947 F475 FA1D"
            # Eric R. Sandeen
            "2B81 8591 9E8D 2489 8186  9DED 20AE 1692 E13D DEE0"
          ];
        };
      };
    };
  
  