n.prev = nil
	} else {
		n.next = parent.kids
		n.prev = nil
		if n.next != nil {
			n.next.prev = n
		}
		parent.kids = n
	}
}

func (n *http2priorityNode) addBytes(b int64) {
	n.bytes += b
	for ; n != nil; n = n.parent {
		n.subtreeBytes += b
	}
}

// walkReadyInOrder iterates over the tree in priority order, calling f for each node