@Override
  public SelLong field(SelString field) {
    String fieldName = field.getInternalVal();
    if ("SUNDAY".equals(fieldName)) {
      return SelLong.of(DateTimeConstants.SUNDAY);
    }
    throw new UnsupportedOperationException(type() + " DO NOT support accessing field: " + field);
  }
@Test
  public void testSundayField() {
    SelLong res = SelMiscFunc.INSTANCE.field(SelString.of("SUNDAY"));
    assertEquals(7, res.longVal());
  }