anchor.diff:  
       {noreply, State#state{impressions=Impressions1}};
   
  +handle_info(check_convergence, #state{actor=Actor}=State) ->
  +    {ok, {TotalEvents, _}} = lasp:query(convergence_id()),
  +
  +    case TotalEvents == max_impressions() * client_number() of
  +        true ->
  +            lager:info("Convergence reached on node ~p", [node()]),
  +            lasp:update(convergence_id(), {snd, true}, Actor);
  +        false ->
  +            schedule_check_convergence()
  +    end,
  +
  +    {noreply, State};
  +
   handle_info(Msg, State) ->
       lager:warning("Unhandled messages: ~p", [Msg]),
       {noreply, State}.
  
positive.code:     erlang:send_after(?LOG_INTERVAL, self(), log).
  
  %% @private
  max_impressions() ->
      lasp_config:get(simulation_event_number, 30).
  
negative.code: 
              %% Increment counter.
              {ok, _} = lasp:update(Counter, increment, Actor),
              {ok, _} = lasp:update(convergence_id(), {fst, increment}, Actor),
  
              %% Increment impressions.
              Impressions0 + 1
  