docs: private void leftDelete(
                             GBSNode           p,
                             GBSNode           r,
                             Object            deleteKey,
                             DeleteNode        point)
      {
          if (r == null)                 /* There is no upper predecessor         */
              leftDeleteNoPredecessor(p, deleteKey, point);
          else                           /* There is an upper predecessor         */
              leftDeleteWithPredecessor(p, r, deleteKey, point);
      }