  With_element *get_with_element()
  {
    return master_unit()->cloned_from ?
           master_unit()->cloned_from->with_element :
           master_unit()->with_element;
  }
  With_element *get_with_element()
  {
    return master_unit()->cloned_from ?
           master_unit()->cloned_from->with_element :
           master_unit()->with_element;
  }