def addPaddingToBase64String(base64String: str) -> str:
    """
    Return a padded version of a base64String that is not long enough to be decoded by base64.b64decode()

    :param base64String: The base64String that is not long enough to be decoded by base64.b64decode()
    :type base64String: str
    :return: base64String padded with "=" so it can be decoded by base64.b64decode()
    :rtype: str
    """
    return base64String + '=' * (-len(base64String) % 4)