code: public T getUp() {
          if (navigator < 0) {
              return null;
          }
          if (navigator == 0) {
              try {
                  return (T)(items[navigator]);
              } finally {
                  if (wasFullAtleastOnce) {
                      navigator = size - 1;
                  } else {
                      navigator = emptyItemIndex - 1;
                  }
              }
          }
          return (T)(items[navigator--]);
      }
docs: Think of this method conceptually as navigating using down up in history
  list of commands.
  @return