anchor.diff:      io:format("Unknown message received: ~p~n", [Msg]),
       {noreply, S}.
   
  +code_change(_OldVsn, State, _Extra) ->
  +    {ok, State}.
  +
   terminate(_Reason, _State) ->
       ok.
   
  
positive.code: 
  return(UUID) ->
      gen_server:call(?MODULE, {return, UUID}).
  
  init([]) ->
      lmq_queue:start(),
  
negative.code: -module(lmq_queue_server).
  -behaviour(gen_server).
  -export([start_link/0, push/1, pull/0, complete/1, alive/1, return/1, stop/0]).
  -export([init/1, handle_call/3, handle_cast/2, handle_info/2, code_change/3, terminate/2]).
  -export([test/0]).
  
  -include("lmq.hrl").
  -record(state, {refs=gb_sets:empty(), queue=queue:new()}).
  
  start_link() ->
      gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
  
  push(Data) ->
      gen_server:call(?MODULE, {push, Data}).
  