anchor.diff:  run_built_in(erlang, monitor, 2, [Type, Pid], Info) ->
     #concuerror_info{
        monitors = Monitors,
  -     next_event = #event{event_info = EventInfo} = Event,
  -     processes = Processes} = Info,
  +     next_event = #event{event_info = EventInfo} = Event} = Info,
     ?badarg_if_not(Type =:= process andalso is_pid(Pid)),
     Ref =
       case EventInfo of
  
positive.code:              #concuerror_info{
                  next_event = #event{event_info = EventInfo} = Event
                 } = Info) ->
    case EventInfo of
      %% Replaying...
      #builtin_event{result = OldResult} -> {OldResult, Info};
      %% New event...
      undefined ->
        ?debug_flag(?send, {send, Recipient, Message}),
        Pid =
          case is_pid(Recipient) of
            true -> Recipient;
            false ->
              {P, Info} = run_built_in(erlang, whereis, 1, [Recipient], Info),
              P
          end,
        case is_pid(Pid) of
          true ->
            MessageEvent =
              #message_event{
                 cause_label = Event#event.label,
                 message = #message{data = Message, message_id = make_ref()},
                 recipient = Pid},
            NewEvent = Event#event{special = {message, MessageEvent}},
            ?debug_flag(?send, {send, successful}),
            {Message, Info#concuerror_info{next_event = NewEvent}};
          false -> error(badarg)
        end
    end;
  run_built_in(erlang, process_flag, 2, [trap_exit, Value],
               #concuerror_info{trap_exit = OldValue} = Info) ->
  
negative.code:       %% New event...
        undefined -> make_ref()
      end,
    {IsActive, Info} = run_built_in(erlang, is_process_alive, 1, [Pid], Info),
    case IsActive of
      true -> true = ets:insert(Monitors, {Pid, {Ref, self()}, active});
      false -> ok
    end,
    NewInfo =
      case EventInfo of
        %% Replaying...
        #builtin_event{} -> Info;
        %% New event...
        undefined ->
          case IsActive of
            false ->
              Message =
                #message{data = {'DOWN', Ref, process, Pid, noproc},
                         message_id = make_ref()},
              MessageEvent =
                #message_event{
                   cause_label = Event#event.label,
                   message = Message,
                   recipient = self()},
              NewEvent = Event#event{special = {message, MessageEvent}},
              Info#concuerror_info{next_event = NewEvent};
            true -> Info
          end
      end,
    {Ref, NewInfo};
  