@carlossg this is what I am talking about. Since `backoff_if_unfound` makes lots of actions synchronous, I'd better preferred `wait` method based on Operation status. I have following suggestions: 
- providing option to determine what kind of action should  be used: synchronous or asynchronous;
- return `Operation` instance with every method that perform GCE action (create, remove resource and etc.) to give user chance to call `wait` on operation if it is needed. So you can do smth like  `server.reboot.wait`, it's more comfortable imo than creating operation manually. Also `wait` can take block and other parameters.

The like better the last variant.