anchor.diff:  fetchurl {
     name = "dnssec-root-2010-07-15";
     url = "https://data.iana.org/root-anchors/root-anchors.xml";
  -  sha256 = "0higqh4wkpwbv0jnx8r4wgl7zmxzbv58m6pn0zi9yg2mq9i3q6hm";
  +  sha256 = "1ifni2nzb0yxzh23zmah0hnma1cj597jp59dsamvna8sja0jwykv";
     downloadToTemp = true;
     recursiveHash = true;
     postFetch = ''
  
positive.code:     { if (/<Digest>/) {print $3;} }
      ' $downloadedFile | tee hash
      [ -n "$(cat hash)" ]
  
      echo -n "Root Key Id (root-anchors.xml): "
      awk '
  
negative.code:     {
        getline id<"xml-id";
        getline hash<"hash";
        getline hashtype<"hash-type";
        print "Domain: " $1;
        print "Id: " id;
        print "Hash: " hash;
        print "HashType: " hashtype;
        print "Flags: " $5;
        print "Protocol: " $6;
        print "Algorithm: " $7;
  