code: protected Node<K, V> unlinkRightChild(Node<K, V> n) {
          Node<K, V> left = n.o_c;
          if (left == null || left.y_s == n) {
              return null;
          }
          Node<K, V> right = left.y_s;
          left.y_s = n;
          right.y_s = null;
          return right;
      }
docs: Unlink the right child of a node.
  
  @param n
  the node
  @return the right child after unlinking