Consider the following case (playground):

main.py

import module

# Missing explicit import of submodule:
# import module.submodule

print(module.submodule.SubmoduleClass)

module/__init__.py

from module.submodule import SubmoduleClass

module/submodule.py

class SubmoduleClass: ...

This works at runtime due to a quirk in module resolution (the from module.submodule import SubmoduleClass import implicitly stores submodule as an attribute on module, thanks @AlexWaygood).

It is not considered good practice to rely on this, but people will probably write code that does so. Neither pyright nor mypy report any errors here. Should we attempt to model this behavior as well?