Revision e2dacbee-d7db-4e82-802c-b212e84b97a5 - Stack Overflow

You should read [this](https://docs.python.org/3/reference/import.html).

By putting the files at the same level, you put them is the same package level.
In your case, you need to get this architecture:

 mypackage
 ├── __init__.py
 ├── one.py # contains "import two"
 └── two
 ├── __init__.py
 ├── two.py # contains "import three"
 └── three
    ├── __init__.py
    └── three.py

And then, you can access the package with:

 import mypackage.one
 import mypackage.one.two
 import mypackage.one.two.three