@Override
    public void addChange(int first, int second) {
      Change change = new Change(myIndex1, myIndex2, first, second, null);
      if (myLastChange != null) myLastChange.link = change;
      else myFirstChange = change;
      myLastChange = change;
      skip(first, second);
    }
@Override
    public void addChange(int first, int second)