anchor.diff:  
     getdns = stdenv.mkDerivation rec {
       pname = "getdns";
  -    version = "1.7.0";
  +    version = "1.7.2";
       outputs = [ "out" "dev" "lib" "man" ];
   
       src = fetchurl {
  
positive.code: 
    stubby = stdenv.mkDerivation rec {
      pname = "stubby";
      version = "0.4.0";
      outputs = [ "out" "man" "stubbyExampleJson" ];
  
      inherit (getdns) src;
  
negative.code:           with builtins;
            concatStringsSep "-" (splitVersion version)
          }/${pname}-${version}.tar.gz";
        sha256 =
          # upstream publishes hashes in hex format
          "db89fd2a940000e03ecf48d0232b4532e5f0602e80b592be406fd57ad76fdd17";
      };
  
      nativeBuildInputs = [ cmake doxygen ];
  