harness.check(s.current(), 'G');
s.next();
harness.check(s.current(), CharacterIterator.DONE);
s.first();
harness.check(s.current(), 'A');
s.previous();
harness.check(s.current(), 'A');
// try results for a subset of the characters
s = new Segment(ch, 3, 3);
harness.check(s.current(), 'A');