anchor.diff:      {{value, Transition}, TmpLidTrace} = queue:out_r(LidTrace),
       NewLast = {Lid, {Spawn, ChildLid}},
       NewLidTrace = queue:in(NewLast, TmpLidTrace),
  -    ?f_debug("Child adding more backtracks...\n"),
  -    NewTrace = add_all_backtracks_trace(ChildTr, Trace),
  -    case NewTrace =/= Trace of
  -        true ->
  -            ?f_debug("CHANGED!\n");
  -        false ->
  -            ?f_debug("NOT CHANGED!\n")
  -    end,
  -    {TraceTop#trace_state{last = NewLast,
  -                          enabled = NewEnabled,
  -                          blocked = NewBlocked,
  -                          nexts = NewNexts,
  -                          lid_trace = NewLidTrace},
  -     NewTrace};
  +    TraceTop#trace_state{last = NewLast,
  +                         enabled = NewEnabled,
  +                         blocked = NewBlocked,
  +                         nexts = NewNexts,
  +                         lid_trace = NewLidTrace};
   handle_instruction_al({Lid, {'receive', [_HasMatching, _HasAfter]}} = Transition,
  -                      _ClockVector, TraceTop, ReceiveDetails, Trace) ->
  +                      _ClockVector, TraceTop, ReceiveDetails) ->
       #trace_state{lid_trace = LidTrace} = TraceTop,
       {{value, Transition}, TmpLidTrace} = queue:out_r(LidTrace),
       NewLast =
  
positive.code:                     AllAddState = add_all_backtracks(Next, LocalAddState),
                      %% ?f_debug("AAS: ~p\n",[AllAddState]),
                      UpdState = update_trace(Selected, ClockVector, Next, AllAddState),
                      %% ?f_debug("US : ~p\n",[UpdState]),
                      NewState = add_some_next_to_backtrack(UpdState),
                      explore(NewState)
              end;
          none ->
  
negative.code: max_cv(CV1, CV2) ->
      Merger = fun(_Key, V1, V2) -> max(V1, V2) end,
      dict:merge(Merger, CV1, CV2).
  
  add_all_child_backtracks({spawn, unknown}, State) ->
      #dpor_state{trace = [TraceTop|_]} = State,
      #trace_state{last = {_, {spawn, ChildLid}}, enabled = Enabled,
                   nexts = Nexts} = TraceTop,
      case ordsets:is_element(ChildLid, Enabled) of
          true ->
              ChildNext = dict:fetch(ChildLid, Nexts),
              add_all_backtracks({ChildLid, ChildNext}, State);
          false ->
              State
      end;
  add_all_child_backtracks(_Else, State) ->
      State.    
  
  %% STUB
  add_some_next_to_backtrack(State) ->
  