anchor.diff:  handle_info(_Info, State) ->
       {noreply, State}.
   
  -terminate(_Reason, _State) ->
  +terminate(_Reason, State) ->
  +    {ok, cancel} = timer:cancel(State#state.tref),
       ok.
  +
  +
   
   code_change(_Vsn, State, _Extra) ->
       {ok, State}.
  
positive.code:     gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
  
  init([]) ->
      {ok, _TRef} = timer:send_interval(timer:seconds(1), doit),
      {ok, #state{last = stamp()}}.
  
  handle_call(_Req, _From, State) ->
      {reply, {error, badrequest}, State}.
  
  
negative.code: 
  -behaviour(gen_server).
  -export([start/0, start_link/0]).
  -export([stop/0]).
  -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
  
  -record(state, {last, tref}).
  
  start() ->
      gen_server:start({local, ?MODULE}, ?MODULE, [], []).
  