python - cannot import a module after os.chdir()

I have a python file with the class A
defined in it in a different directory than the one I am working in. I want to import a
module from that class in my script. I wrote something like this in
jupyter:

import
            os
parent_dir = 'path/to/class'
os.chdir(parent_dir) 
from
            A import a

It works
perfectly fine and I get to execute the program. However when I run the script in the
same directory from the terminal, I get this
error:

ModuleNotFoundError: No
            module named
            'a'

I put a
os.getcwd() before the error to make sure it is in the same
directory, and when I go to that directory from the terminal and import the module
directly there are no errors. I wonder why I get this error when running the script.

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Answer

Don't use os.chdir,
because it changes a global state, that can lead to unexpected behaviour somewhere
else.

Expand
sys.path:

import
            sys
sys.path.append('/absolute/path/to/module')