How to import module to service code in Python?

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Hello, everyone! I'm writing a ROS service for my robot in Python. I have one file which contains all code in arm_mover.py . The code has become too big and I need to replace a part to another module helpers.comm. But I don't understand how I must import my new module to the main script. Lines like 'import helpers.comm' or 'import package_name.helpers.comm' don't work.

/package_root
 |--/scripts
 |   |-----arm_mover.py
 |--/src
     |-----/helpers
           |--__init__.py
           |--comm.py

Thanks, for help.