Python3 Help Modules <module> always returns Traceback error "AttributeError: 'NoneType' object has no attribute 'loader'"
Ubuntu does not have such unasync package in the official repository.
Repology says that it is available via PyPi.
So you have to install this package by
sudo apt-get install python3-pip
sudo pip3 install unasync
and then retry to access it and its help.