static int indexOf(CharSequence cs, CharSequence searchChar, int start) {
        return cs.toString().indexOf(searchChar.toString(), start);
    }
@Test
    public void testIndexOf() {
        Assertions.assertEquals(-1, Utils.indexOf("bar", "foo", 0));
        Assertions.assertEquals(-1, Utils.indexOf("bar", "a", 2));
        Assertions.assertEquals(1, Utils.indexOf("bar", "a", 0));
        Assertions.assertEquals(1, Utils.indexOf("bar", "a", 1));
    }