public boolean finished() {
    if (actor == null) return false ;
    if (this == actor.mind.rootBehaviour()) {
      if (priorityFor(actor) <= 0) return true ;
    }
    if (nextStep() == null) {
      if (verbose) I.sayAbout(actor, "NO NEXT STEP") ;
      return true ;
    }
    return false ;
  }