anchor.diff:  %% @doc Find a zone for a given qname.
   -spec find_zone(dns:dname()) -> #zone{} | {error, zone_not_found} | {error, not_authoritative}.
   find_zone(Qname) ->
  -  find_zone(normalize_name(Qname), get_authority(Qname)).
  +  find_zone(erldns:normalize_name(Qname), get_authority(Qname)).
   
   %% @doc Find a zone for a given qname.
   -spec find_zone(dns:dname(), {error, any()} | {ok, dns:rr()} | [dns:rr()] | dns:rr()) -> #zone{} | {error, zone_not_found} | {error, not_authoritative}.
  
positive.code: find_zone(Qname, Authorities) when is_list(Authorities) ->
    find_zone(Qname, lists:last(Authorities));
  find_zone(Qname, Authority) when is_record(Authority, dns_rr) ->
    Name = normalize_name(Qname),
    case dns:dname_to_labels(Name) of
      [] -> {error, zone_not_found};
      [_|Labels] ->
  
negative.code: build_named_index([R|Rest], Idx) ->
    case dict:find(R#dns_rr.name, Idx) of
      {ok, Records} ->
        build_named_index(Rest, dict:store(erldns:normalize_name(R#dns_rr.name), Records ++ [R], Idx));
      error ->
        build_named_index(Rest, dict:store(erldns:normalize_name(R#dns_rr.name), [R], Idx))
    end.
  
  -spec(sign_zone(erldns:zone()) -> erldns:zone()).
  sign_zone(Zone = #zone{keysets = []}) ->
  