s = new Segment(ch, 3, 3);
harness.check(s.current(), 'A');
s.last();
harness.check(s.current(), 'F');
s.next();
harness.check(s.current(), CharacterIterator.DONE);
s.first();
harness.check(s.current(), 'D');
s.previous();
harness.check(s.current(), 'D');
}