code: def update_node(self, node, diff=None):
          
          lb = node.parent
          if not lb:
              raise exc.UnattachedNode("No parent Load Balancer for this node "
                      "could be determined.")
          if diff is None:
              diff = node._diff()
          req_body = {"node": diff}
          resp, body = self.api.method_put("/loadbalancers/%s/nodes/%s" %
                  (lb.id, node.id), body=req_body)
          return resp, body
docs: Updates the node's attributes.