Python3 Function to Detect if the Caller Is the Main Source

main_utils.py

import inspect
from types import FrameType
from typing import cast


def is_caller_main() -> bool:
    # See https://stackoverflow.com/a/57712700/
    caller_frame = cast(FrameType, cast(FrameType, inspect.currentframe()).f_back)
    caller_script_name = caller_frame.f_locals['__name__']

    return caller_script_name == '__main__'

test.py

#!/usr/bin/env python3

# Use case

import main_utils


if main_utils.is_caller_main():
    print('MAIN')
else:
    print('NOT MAIN')