python3 module import from subpackage

Question

Let's assume I do have such package structure:

foobar/
    - foo/bar.py
    - ...
    main.py

Shall I use:

from foo import bar 

or

import foo.bar

or

import foo.bar as bar

Currently, I do from foo import bar as I find it correct but I want to double check it (I think Python documentation recommends this also).