@Before
 public void setUp() {
   final RegularExpression expr = Repetition.of(CharacterClass.character('e'));
   ndfaFactory = Ndfas.ndfaFactory(expr);
 }
 @Before
 public void setUp() {
   final RegularExpression expr = CharacterClass.wildcard();
   ndfaFactory = Ndfas.ndfaFactory(expr);
 }