get_fnc_from_line should return falsy if owner function is private/has dunder

[kremrik]

In the below example, the call to main in the main block will return the main function itself because it's the first function definition found above the call

from test import fnc

def main():
    fnc()

if __name__ == "__main__":
    main()

[kremrik]

this means main blocks should be considered their own function, or that the calls they make to reference the file itself