anchor.diff:          {'$gen_component', bp, breakpoint, step, StepperPid} ->
               TmpBPState = bp_state_set_bpstepped(BPState, true),
               NewBPState = bp_state_set_bpstepper(TmpBPState, StepperPid),
  +            ?TRACE_BP_STEPS("~n"
  +                            "*** Start handling message...~n"
  +                            "    Process: ~p (~p)~n"
  +                            "    Message: ~.0p~n",
  +                            [self(), pid_groups:group_and_name_of(self()),
  +                             Message]),
               {Options, Slowest, NewBPState};
           {'$gen_component', bp, breakpoint, cont} ->
               T1BPState = bp_state_set_bpactive(BPState, false),
  
positive.code:     Pid !  {'$gen_component', bp, breakpoint, step, self()},
      receive {'$gen_component', bp, breakpoint, step_done,
               _GCPid, Module, On, Message} ->
              ?TRACE_BP_STEPS("~p ~p:~p/2 handled message ~w~n",
                              [_GCPid, Module, On, Message]),
              {Module, On, Message}
      end.
  
  
negative.code: %-define(TRACE_BP(X,Y), ct:pal(X,Y)).
  -define(TRACE_BP(X,Y), ok).
  %% userdevguide-begin gen_component:trace_bp_steps
  %-define(TRACE_BP_STEPS(X,Y), io:format(X,Y)).     %% output on console
  %-define(TRACE_BP_STEPS(X,Y), ct:pal(X,Y)).        %% output even if called by unittest
  %-define(TRACE_BP_STEPS(X,Y), io:format(user,X,Y)). %% clean output even if called by unittest
  -define(TRACE_BP_STEPS(X,Y), ok).
  %% userdevguide-end gen_component:trace_bp_steps
  
  