anchor.diff:  %% define macros for the tuple positions to use them also in guards.
   -define(MOD,         1).
   -define(HAND,        2).
  --define(USTATE,      3).
  --define(OPTS,        4).
  --define(SLOWEST,     5).
  --define(BPS,         6).
  --define(BP_ACTIVE,   7).
  --define(BP_QUEUE,    8).
  --define(BP_STEPPED,  9).
  --define(BP_STEPPER,  10).
  +%-define(OPTS,        3).
  +%-define(SLOWEST,     4).
  +-define(BPS,         3).
  +-define(BP_ACTIVE,   4).
  +-define(BP_QUEUE,    5).
  +-define(BP_STEPPED,  6).
  +-define(BP_STEPPER,  7).
   
   %% userdevguide-begin gen_component:behaviour
   -ifdef(have_callback_support).
  
positive.code: %%   not in a breakpoint. A selective receive of breakpoint messages,
  %%   provides further bp instructions when needed inside a bp.
  %%%%%%%%%%%%%%%%%%%%
  -spec on(comm:message(), gc_state()) -> gc_state() | ok.
  on(GCMsg, State) when is_tuple(GCMsg)
                        andalso '$gen_component' =:= element(1, GCMsg) ->
      on_gc_msg(GCMsg, State);
  on({ping, Pid}, State) ->
      %% handle failure detector messages
      comm:send(Pid, {pong}, [{channel, prio}]),
      State;
  on({send_to_group_member, Processname, Msg}, State) ->
      %% forward a message to group member by its process name
      %% initiated via comm:send/3 with group_member
      Pid = pid_groups:get_my(Processname),
  
negative.code: -type gc_state() ::
          { module(),
            handler(),
            [bp()],             %% registered breakpoints
            boolean(),          %% bp active?
            [bp_msg()],         %% queued bp messages
  