QMessageBox expects "StandardButtons" and fails

This code seems to fail with the stubs:

```
QMessageBox.question(self, "Confirm", "Are you sure?", QMessageBox.Yes | QMessageBox.No)
```

Tells me: 

```
Argument 4 to "question" of "QMessageBox" has incompatible type "int"; expected "Union[StandardButtons, StandardButton]"
```

But the code should work, should it not?