anchor.diff:  %%
   
   %% @private
  -send_error(Message, State) ->
  -    Headers = [{"message", atom_to_list(Message)},
  +send_error(Msg, State) -> send_error(Msg, [], State).
  +
  +%% @private
  +send_error(Msg, Details, State) ->
  +    Headers = [{"message", atom_to_list(Msg)},
                  ?CONTENT_TEXT,
                  ?VERSION_HEADER],
  -    case send_frame("ERROR", Headers, [], State) of
  -        {noreply, NewState} -> {stop, Message, NewState};
  +    case send_frame("ERROR", Headers, Details, State) of
  +        {noreply, NewState} -> {stop, Msg, NewState};
           Error               -> Error
       end.
   
   %% @private
  -send_frame(Command, Headers, Body, State) ->
  -    send_frame(#stomp_frame{command = Command, headers = Headers, body = Body}, State).
  +send_frame(Cmd, Headers, Body, State) ->
  +    send_frame(#stomp_frame{command = Cmd, headers = Headers, body = Body}, State).
   
   -spec send_frame(restomp:frame(), inet:socket()) -> #s{}.
   %% @private
  
positive.code: 
  %% @private
  ack(Frame, State) ->
      Fun = fun(H) -> restomp:header(Frame, H) end,
      case {Fun("message-id"), Fun("subscription")} of
          {{ok, _Id}, {ok, _Sub}} ->
              {noreply, State};
          {not_found, _Sub} ->
              send_error(no_message_id, State);
          {_Id, not_found} ->
              send_error(no_subscription, State)
      end.
  
  %% @private
  nack(Frame, State) ->
      Fun = fun(H) -> restomp:header(Frame, H) end,
      case {Fun("message-id"), Fun("subscription")} of
          {{ok, _Id}, {ok, _Sub}} ->
              {noreply, State};
          {not_found, _Sub} ->
              send_error(no_message_id, State);
          {_Id, not_found} ->
              send_error(no_subscription, State)
      end.
  
  %% @private
  
negative.code: 
  %% @private
  subscribe(Frame, State) ->
      case ensure_headers(["ack", "id", "destination"], Frame) of
          {ok, ["client", _Id, Dest]} ->
              case split_destination(Dest) of
                  {queue, _Topic, _Queue} -> {noreply, State};
                  _Other                  -> send_error(invalid_destination, State)
              end;
          {ok, [_Ack, _Id, _Dest]} ->
              send_error(must_set_ack_client, State);
          {error, Msg, Detail} ->
              send_error(Msg, Detail, State)
      end.
  
  %% @private
  