importing an attribute

[Gribouillis]

Can say the last version is more user friendly,if try to figure out a package without looking at doc.

You can use pkgutil for this, the following code should work

import pkgutil
import botocore
print([t[1] for t in pkgutil.iter_modules(botocore.__path__)])

Actually, I already wrote a script for this task in this forum list_subpackages.py
With this you only need to call on the commandline

Output:
list_subpackages.py botocore

It also lists subsubpackages recursively.