anchor.diff:  -export([
       is_blocked/1,
       is_blocked/2,
  +    is_blocked/3,
       status/1,
       status/2,
  +    status/3,
  +    dnswl_list/0,
       dnsbl_list/0,
   
       test/0
  
positive.code: 
  -spec is_blocked(inet:ip_address()) -> boolean().
  is_blocked(IP) ->
      is_blocked(IP, dnsbl_list()).
  
  -spec is_blocked(inet:ip_address(), list(string())) -> boolean().
  is_blocked(IP, RTBLs) ->
      case status(IP, RTBLs) of
          {ok, {blocked, _DNSBL}} -> true;
          _ -> false
      end.
  
  -spec status(inet:ip_address()) -> {ok, {blocked, list()}} | {ok, notlisted} | {error, term()}.
  status(IP) ->
      status(IP, dnsbl_list()).
  
  -spec status(inet:ip_address(), list()) -> {ok, {blocked, list()}} | {ok, notlisted} | {error, term()}.
  status(IP, DNSBLs) ->
      Dotted = reverse(IP),
      status_1(Dotted, DNSBLs).
  
  status_1(_Dotted, []) ->
      {ok, notlisted};
  
negative.code:     {ok, notlisted};
  check_addr_list(DNSBL, List) ->
      List1 = lists:filter(fun
                              ({127,0,_,_}) -> true;
                              (_) -> false
                           end,
                           List),
  