Add/document support for `print` method in `getattr` interface

[leonardt]

[David-Durst]

I believe I just ran into this issue.

It would be helpful to have documentation on how the appropriate way to print system internals. My current approach is https://github.com/David-Durst/aetherling/blob/ea5fdb63d03314268eb149b6db5a44c59811b671/tests/test_map.py#L150, which is quite ugly and required some hacking to figure out.