So yeah, @carlossg, because of backoff, it's is not completely async, but I want it to be. I really don't like the `wait` method adding. That's a pretty big departure from how the rest of Fog works (AFAIK). Personally, I think the right API is to stick close to what we have already:

```ruby
disk = compute.disks.new(size_gb: 20)
disk.wait_for { ready? }
```

And if we check to make sure the operation isn't pending, that should be all we need. Unless I am missing something here?