[web2py] How to check if a given user in logged in an external private python script?

[Saurabh Kumar]

By external python script, I mean a python script run using following 
command:

python web2py.py -S app_name -M -R applications/app_name/private/script.py

I have to check if the user with a given user_id is 'logged in' inside this 
script.

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