Python void return type annotation

Question

In python 3.x, it is common to use return type annotation of a function, such as:

def foo() -> str:
    return \"bar\"

What is the correct a

Answer 1

This is straight from PEP 484 -- Type Hints documentation:

When used in a type hint, the expression None is considered equivalent to type(None).

And, as you can see most of the examples use None as return type.