anchor.diff:  
   -record(request, {requester, foldfun, acc}).
   -record(request_error, {requester, reason}).
  --record(state, {worker = undefined, queue = []}).
  +-record(state, {worker = undefined, queue = [], worker_start = undefined}).
   
   -define(SERVER, ?MODULE).
   
  
positive.code: %%                                      {stop, Reason, State}
  %% Description: Handling cast messages
  %%--------------------------------------------------------------------
  handle_cast({worker_done, Worker, ResultQueue}, #state{worker = Worker} = State) ->
      lists:foreach(fun(#request{requester = Requester, acc = AccOut}) ->
  			  gen_server:reply(Requester, {ok, AccOut});
  		     (#request_error{requester = Requester, reason = Reason}) ->
  			  gen_server:reply(Requester, {error, Reason})
  		  end, ResultQueue),
  
      State2 = State#state{worker = undefined},
      State3 = maybe_start(State2),
      {noreply, State3}.
  
  %%--------------------------------------------------------------------
  %% Function: handle_info(Info, State) -> {noreply, State} |
  
negative.code:     NewWorker = spawn_link(fun() ->
  				   worker(Queue)
  			   end),
      State#state{worker = NewWorker, queue = [], worker_start = util:mk_timestamp_us()}.
  
  
  worker(Queue) ->
  