from typing import List


def hello_world(cities: List[str] = ["Berlin", "Paris"]) -> bool:
    """
    Hello world function.

    Arguments:
    - cities: List of cities in which 'hello world' is posted.

    Return:
    - success: Whether or not function completed successfully.
    """

    try:
        [print("Hello {}!".format(c)) for c in cities]  # for loop one-liner
        return True

    except KeyboardInterrupt:
        return False

    finally:
        pass