assertEquals("test\nkkk\n", c.getAsDoc().get());
assertFalse(c.next());
assertEquals("", c.get());
assertTrue(c.prev());
assertEquals("kkk", c.get());
assertTrue(c.prev());
assertEquals("test", c.get());
c.update("");
c.commit();
assertEquals("test\nkkk\n\n", c.getAsDoc().get());