```
In [158]: 'a' in 'qcow2' or 'qcow2v3' or 'qed'
Out[158]: 'qcow2v3'
```
What do you want to check here?

```
image_is_checkable = self.image_format in ['qcow2', 'qcow2v3', 'qed']
```
sounds what you really need.