anchor.diff:  -record(state, {
   	universaltime = undefined :: undefined | calendar:datetime(),
   	rfc1123 = <<>> :: binary(),
  -	tref = undefined :: undefined | timer:tref()
  +	tref = undefined :: undefined | reference()
   }).
   
   %% API.
  
positive.code: -spec handle_info(any(), State) -> {noreply, State} when State::#state{}.
  handle_info(update, #state{universaltime=Prev, rfc1123=B1, tref=TRef0}) ->
  	%% Cancel the timer in case an external process sent an update message.
  	erlang:cancel_timer(TRef0),
  	T = erlang:universaltime(),
  	B2 = update_rfc1123(B1, Prev, T),
  	ets:insert(?MODULE, {rfc1123, B2}),
  
negative.code: 	ets:insert(?MODULE, {rfc1123, B}),
  	{ok, #state{universaltime=T, rfc1123=B, tref=TRef}}.
  
  -type from() :: {pid(), term()}.
  -spec handle_call
  	(stop, from(), State) -> {stop, normal, stopped, State}
  	when State::#state{}.
  handle_call(stop, _From, State=#state{tref=TRef}) ->
  	{stop, normal, stopped, State};
  handle_call(_Request, _From, State) ->
  	{reply, ignored, State}.
  