How to get extern data for my system exception subroutine?

Your question is not very clear. First, format your code as described in the about post. That makes it formatted so it will be much clearer.

I created a small example, a file called in the current working directory that contains:

    class UnexpectedText():
        quote = "Nobody expects the Spanish inquisition"

    unexpected_instance = UnexpectedText()

First we get the instance from importables:

>>> from importables import unexpected_instance
>>> print(unexpected_instance.quote)
Nobody expects the Spanish inquisition

We can also get the whole namespace as names, you know the syntax:

>>> import importables
>>> print(importables.unexpected_instance.quote)
Nobody expects the Spanish inquisition

How does this not answer your question?