@Test
 public void convertToIndex() {
   assertThat(A.ordinal(), is(0));
   assertThat(B.ordinal(), is(1));
   assertThat(C.ordinal(), is(2));
   assertThat(X.ordinal(), is(23));
   assertThat(Y.ordinal(), is(24));
   assertThat(Z.ordinal(), is(25));
 }