anchor.diff:      Pid ! Message,
       State#state{queue = Q2}.
   
  +notify_async(#state{async = Pid}, Msg) ->
  +    case is_pid(Pid) of
  +        true  -> Pid ! {pgsql, self(), Msg};
  +        false -> false
  +    end.
  +
   %% -- backend message handling --
   
   %% AuthenticationOk
  
positive.code:     {noreply, State2} = on_message(Other, State),
      {noreply, State2, Timeout}.
  
  on_message({$N, Data}, State) ->
      %% TODO use it
      {notice, pgsql_wire:decode_error(Data)},
      {infinity, State};
  
  %% ParameterStatus
  on_message({$S, Data}, State) ->
  
negative.code:                                  {Name, Value}),
      {noreply, State#state{parameters = Parameters2}};
  
  %% NotificationResponse
  on_message({$A, <<Pid:?int32, Strings/binary>>}, State) ->
      case pgsql_wire:decode_strings(Strings) of
          [Channel, Payload] -> ok;
          [Channel]          -> Payload = <<>>
      end,
      %% TODO use it
      notify_async(State, {notification, Channel, Pid, Payload}),
      {noreply, State}.
  
  hex(Bin) ->
      HChar = fun(N) when N < 10 -> $0 + N;
  