How to indicate [this type] or None

[arush]

It is very common for functions to return a type or None. In typescript you can say string | null and the checker will warn you where you forgot to defend against potential null instances. How do you indicate that something may be a type or None ?

[dark]

In Python, that would be Optional[str], that is a shorthand for Union[str, None].
You can find a full description of these type annotations, and more, at https://docs.python.org/3/library/typing.html