If you change the method signatures to use `**kwargs` then these calls will need to change by either unrolling the kwargs dict via `**` or by unrolling it by specifying the parameters and values yourself.

So either
```python
msg = super(PollRequest, cls).from_dict(d, **kwargs)
```
Or something similar to
```python
msg = super(PollRequest, cls).from_dict(d, content_bindings=d.get('content_bindings'), subscription_id=d.get('subscription_id'), ...)
```