To help with circular import, we switched a few years ago to lazily importing submodules on demand, and never switched back.

Just add to your __init__.py files:

import importlib

def __getattr__(submodule_name):

    return importlib.import_module('.' + submodule_name, __package__)

And then just import the root module and use it without ever needing to import individual submodules:

import foo

def bar():

    return foo.subfoo.bar() # foo.subfoo is imported when the function is first executed instead of when it is parsed, so no circular import happen