def input_yn(message):
    """Prompt for a yes or no

    Summary: Prompt a y/n question
    Attributes:
        @param message: question requiring y/n answer from user
    Returns: Boolean value of the user's answer
    """
    response = input(message + " (y/n): ").strip().lower()
    valid_responses = ('n', 'y')
    if response and response[0] in valid_responses:
        return bool(valid_responses.index(response))
    else:
        return input_yn(message)