anchor.diff:  is_next_enabled(_) -> true.
   
   %% Handle instruction is broken in two parts to reuse code in replay.
  -handle_instruction(Transition, ClockVector, TraceTop, Trace) ->
  +handle_instruction(Transition, ClockVector, TraceTop) ->
       Variables = handle_instruction_op(Transition),
  -    handle_instruction_al(Transition, ClockVector, TraceTop, Variables, Trace).
  +    handle_instruction_al(Transition, ClockVector, TraceTop, Variables).
   
   handle_instruction_op({Lid, {Spawn, _Info}}) when Spawn =:= spawn; Spawn =:= spawn_link ->
       ParentLid = Lid,
  
positive.code: %% - add new entry with new entry
  %% - wait any possible additional messages
  %% - check for async
  update_trace({Lid, Cmd} = Selected, ClockVector, Next, State) ->
      ?f_debug("Sele: ~w Next: ~w\n",[Selected, Next]),
      #dpor_state{trace = [TraceTop|_] = Trace} = State,
      #trace_state{i = I, enabled = Enabled, blocked = Blocked,
  
negative.code:             _Else -> {Lid, {'receive', ReceiveDetails}}
          end,
      NewLidTrace = queue:in(NewLast, TmpLidTrace),
      TraceTop#trace_state{last = NewLast, lid_trace = NewLidTrace};
  handle_instruction_al(_Transition, _ClockVector, TraceTop, {}) ->
      TraceTop.
  
  check_blocked(TraceTop, ClockVector) ->
      #trace_state{blocked = Blocked, enabled = Enabled, nexts = Nexts} = TraceTop,
  