This is different from regular packages which are self-contained meaning all parts live in the same directory hierarchy.

google_pubsub/ <- Package 1 google/ <- Namespace package (there is no __init__.py) cloud/ <- Namespace package (there is no __init__.py) pubsub/ <- Regular package (with __init__.py) __init__.py <- Required to make the package a regular package foo.py google_storage/ <- Package 2 google/ <- Namespace package (there is no __init__.py) cloud/ <- Namespace package (there is no __init__.py) storage/ <- Regular package (with __init__.py) __init__.py <- Required to make the package a regular package bar.py