- Manage context when using with the **with** statement (see examples in [the documentation](https://persistentlist.readthedocs.io/en/latest/))
- Rename add() by append() method
- Add extend() method
- use docstrings to provide dynamic documentation for the persistentlist module (see [the official documentation](https://persistentlist.readthedocs.io/en/latest/persistentlist.html))
- add first unit tests