Should cloudpickle.dumps fail when closing over something undefined?

```python
def f():
undefined_function() # this is not defined

import cloudpickle
cloudpickle.dumps(f) # maybe this should throw an exception.
```

The last line succeeds, but I wonder if it would be preferable to raise an exception instead (instead of waiting for it to fail in the corresponding call to `cloudpickle.loads`). Alternatively, is there a way for the caller to configure cloudpickle to raise an exception in the above situation? Or perhaps to detect such a situation?