def to_case_fold(word: str):
    """
    The casefold() method is an aggressive lower() method which
    convert strings to casefolded strings for caseless matching.
    The casefold() method is removes all case distinctions
    present in a string. It is used for caseless matching
    (i.e. ignores cases when comparing).
    For example, German lowercase letter ß is equivalent to ss.
    However, since ß is already lowercase, lower() method
    does nothing to it. But, casefold() converts it to ss.
    :param word: the string to be casefolded
    :return: case-folded string
    """
    return word.casefold()