Gets the first function that was externally called. In other words get the name of the first function in the chain of calls that is not defined in this file.

Get-First-Externally-Called-Name.py

import inspect

def getFirstExternallyCalledName() -> str:
    """
    Gets the name of the first function called externally in a chain of
    called functions within this file.
    """
    # Loop through and get the first caller function not originating
    # from this file.
    frame = inspect.currentframe()
    current_filename = frame.f_code.co_filename
    while frame and current_filename == frame.f_code.co_filename:
        caller_name = frame.f_code.co_name
        frame = getattr(frame, 'f_back')
    return caller_name