anchor.diff:  %% is found, it blocks (i.e. is moved to the blocked set). When a new message
   %% arrives the process is woken up. The check mailbox - block - wakeup loop
   %% is repeated until a matching message arrives.
  --spec rep_receive(fun(() -> any())) -> any().
  +-spec rep_receive(fun((_) -> any())) -> any().
   
   rep_receive(Fun) ->
       rep_yield(),
  
positive.code: 
  %% Debug messages (TODO: define externally?).
  -define(DEBUG, false).
  
  %%%----------------------------------------------------------------------
  %%% Records
  
negative.code:     log("Process ~p spawns process ~p.~n", [ParentLid, ChildLid]),
      NewInfo = dispatcher(Info),
      dispatcher(NewInfo);
  %% Yield message handler.
  %% Receiving a `yield` message means that the process is preempted, but
  %% remains in the active set.
  