code: public final Collection<State> acceptStates() {
  	if(acceptStates == null) {
  	    final Collection<State> states = this.states();
  	    acceptStates = 
  		DSUtil.filterColl(_acceptStates(),
  				  new Predicate<State>() {
  				      public boolean check(State state) {
  					  return states.contains(state);
  				      }
  				  },
  				  new LinkedHashSet<State>());
  	}
  	return acceptStates;
      }
docs: Returns the accepting states of this NFA.  This method returns
  all states returned by {@link #_acceptStates()}, except those
  that are unreachable from the starting state.