@ScalarOperator(LESS_THAN_OR_EQUAL)
    @SqlType(StandardTypes.BOOLEAN)
    public static boolean lessThanOrEqual(@SqlType("unknown") boolean left, @SqlType("unknown") boolean right)
    {
        throw new AssertionError("value of unknown type should all be NULL");
    }
@Test
    public void testLessThanOrEqual()
    {
        assertFunction("NULL <= NULL", BOOLEAN, null);
    }