char[] ch = new char[] {'A', 'B', 'C', 'D', 'E', 'F', 'G'};
Segment s = new Segment(ch, 0, 7);
s.last();
harness.check(s.previous(), 'F');
harness.check(s.previous(), 'E');
harness.check(s.previous(), 'D');
harness.check(s.previous(), 'C');
harness.check(s.previous(), 'B');
harness.check(s.previous(), 'A');
harness.check(s.previous(), CharacterIterator.DONE);
harness.check(s.previous(), CharacterIterator.DONE);