[ROS2 eloquent] import funtion from other python file in launch

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In my launch folder, I have the files node.launch.py and helper.py

In the node.launch.py I want to import the function load from helper.py

from helper import load

when I use the launch file, I get the error:

[ERROR] [launch]: Caught exception in launch (see debug for traceback): Caught exception when trying to load file of format [py]: No module named 'helper'

Do I make something wrong or is it not possible to import functions from other python files in ROS2 launch.py files?