docs: Object insertByRightShift(
      int               ix,
      Object            new1)
    {
      Object old1 = null;
      if (isFull())
        {
          old1 = rightMostKey();
          rightMove(ix+1);
          _nodeKey[ix+1] = new1;
        }
      else
        {
          rightShift(ix+1);
          _nodeKey[ix+1] = new1;
          _population++;
          if (midPoint() > rightMostIndex())
            _nodeKey[midPoint()] = rightMostKey();
        }
      return old1;
    }