anchor.diff:  
   %% internal
   
  -add_worker(Worker, List) ->
  -    [Worker | List].
  +add_worker(Worker, Tab) ->
  +    ets:insert(Tab, Worker), Tab.
   
  -remove_worker(Ref, List) ->
  -    lists:keydelete(Ref, 2, List).
  +remove_worker(Ref, Tab) ->
  +    ets:delete(Tab, Ref), Tab.
   
  -find_worker(Ref, List) ->
  -    lists:keyfind(Ref, 2, List).
  +find_worker(Ref, Tab) ->
  +    case ets:lookup(Tab, Ref) of [] -> false; [Worker] -> Worker end.
   
   notify_caller({Caller, Ref}, Reason) ->
       Caller ! {Ref, {rexi_EXIT, Reason}}.
  
positive.code: -include_lib("eunit/include/eunit.hrl").
  
  -record(st, {
      workers = []
  }).
  
  start_link() ->
  
negative.code:     {noreply, St}.
  
  terminate(_Reason, St) ->
      ets:foldl(fun({Pid, _, _}, _) -> exit(Pid,kill) end, nil, St#st.workers),
      ok.
  
  code_change(_OldVsn, St, _Extra) ->
  