are the methods that your users will call to load/save models with your library. [`ModelHubMixin`] also defines 2
*private* methods (`_save_pretrained` and `_from_pretrained`). Those are the ones you must implement. So to integrate
your library, you should:  
1. Make your Model class inherit from [`ModelHubMixin`].
2. Implement the private methods:
- [`~ModelHubMixin._save_pretrained`]: method taking as input a path to a directory and saving the model to it.