code: private Node<K, V> cutChildren(Node<K, V> n) {
          Node<K, V> child = n.o_c;
          n.o_c = null;
          if (child != null) {
              child.o_s = null;
          }
          return child;
      }
docs: Cut the children of a node and return the list.
  
  @param n
  the node
  @return the first node in the children list