tr = root.descend(sb);
assertEquals(3, sb.getSlicePosition());
assertEquals('o', (char)tr.token);
sb = new SlicedBytes(ArrayBytes.fromString("bro"), 0, 3);
tr = root.descend(sb);
assertEquals(3, sb.getSlicePosition());
assertEquals('o', (char)tr.token);
assertEquals(0, sb.getLength());
sb = new SlicedBytes(ArrayBytes.fromString(""), 0, 0);