Is __init__.py not required for packages in Python 3.3+

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I am using Python 3.5.1. I read the
document and the package section here: href="https://docs.python.org/3/tutorial/modules.html#packages">https://docs.python.org/3/tutorial/modules.html#packages

Now,
I have the following
structure:

/home/wujek/Playground/a/b/module.py

module.py:

class
            Foo:
 def __init__(self):
 print('initializing
            Foo')

Now, while in
/home/wujek/Playground:

~/Playground
            $ python3
>>> import a.b.module
>>>
            a.b.module.Foo()
initializing Foo
            0x100a8f0b8>

Similarly,
now in home, superfolder of
Playground:

~
            $ PYTHONPATH=Playground python3
>>> import
            a.b.module
>>> a.b.module.Foo()
initializing
            Foo
            0x10a5fee10>

Actually,
I can do all kinds of stuff:

~ $
            PYTHONPATH=Playground python3
>>> import a
>>>
            import a.b
>>> import
            Playground.a.b

Why
does this work? I though there needed to be __init__.py files
(empty ones would work) in both a and
b for module.py to be importable when
the Python path points to the Playground
folder?

This seems to have changed from Python
2.7:

~ $ PYTHONPATH=Playground
            python
>>> import a
ImportError: No module named
            a
>>> import a.b
ImportError: No module named
            a.b
>>> import a.b.module
ImportError: No module named
            a.b.module

With
__init__.py in both ~/Playground/a and
~/Playground/a/b it works fine.

Answer

Python 3.3+ has href="https://www.python.org/dev/peps/pep-0420/" rel="noreferrer">Implicit Namespace
Packages that allow it to create a packages without an
__init__.py
file.

Allowing
implicit namespace packages means that the requirement to provide an
__init__.py file can be dropped
completely, and affected ... .

The old way with
__init__.py files still works as in Python
2.