anchor.diff:  
   -type rtm() :: {?RT:key(),
                   {comm:mypid()} | unknown,
  -                Role :: 0..3, %% non_neg_integer(),
  +                Role :: pos_integer(),
                   {Acceptor :: comm:mypid()} | unknown}.
   
   -type rtms() :: [rtm()].
  
positive.code: set_rtmkey(RTMEntry, Val) -> setelement(1, RTMEntry, Val).
  -spec get_rtmpid(rtm()) -> {comm:mypid()} | unknown.
  get_rtmpid(RTMEntry) -> element(2, RTMEntry).
  -spec get_nth(rtm()) -> 0..3.
  get_nth(RTMEntry)    -> element(3, RTMEntry).
  %% -spec get_accpid(rtm()) -> {comm:mypid()} | unknown.
  %% get_accpid(RTMEntry) -> element(4, RTMEntry).
  
negative.code:                    rtms_get_valid_rtmpids/1, rtms_get_valid_accpids/1]}).
  
  -spec rtm_entry_new(?RT:key(), {comm:mypid()} | unknown,
                      pos_integer(), {comm:mypid()} | unknown) -> rtm().
  rtm_entry_new(Key, RTMPid, Nth, AccPid) -> {Key, RTMPid, Nth, AccPid}.
  -spec get_rtmkey(rtm()) -> ?RT:key().
  get_rtmkey(RTMEntry) -> element(1, RTMEntry).
  