#51: Fix default value handling of callbacks in .fit(...)
This MR should close #51 (closed) and makes the following two changes.
- By default
callbacks=None
and is of typeUnion[Callback, List[Callback], None]
so we
- First check if single callback is passed, if yes transform to list
- Secondly if it was not a list of callbacks check if None, if None set to empty list, else keep list
- Improves documentation and type annotations
Edited by Alessandro Maissen