anchor.diff:      {ok, #state{address = Address, port = Port, queue = queue:new()}}.
   
   %% @private
  -handle_call(is_connected, _From, State) ->
  -    case State#state.sock of
  -        undefined ->
  -            {reply, {false, State#state.failed}, State};
  -        _ ->
  -            {reply, true, State}
  -    end;
   handle_call({req, Msg, Timeout}, From, State) when State#state.pending =/= undefined;
                                                      State#state.sock =:= undefined ->
       {noreply, queue_request(new_request(Msg, From, Timeout), State)};
  
positive.code: 
  -export([start_link/2,
           start/2,
           is_connected/1,
           ping/1, ping/2,
           get_client_id/1, get_client_id/2,
  
negative.code: bad_connect_test() ->
      %% Start with an unlikely port number
      {ok, Pid} = start({127,0,0,1}, 65535),
      ?assertEqual({false, [{econnrefused,1}]}, is_connected(Pid)),
      stop(Pid).
  
  pb_socket_test_() ->
      {setup,
  