def strip_quotes(arg):
    """ Strip outer quotes from a string.

     Applies to both single and double quotes.

    :param arg: str - string to strip outer quotes from
    :return str - same string with potentially outer quotes stripped
    """
    quote_chars = '"' + "'"

    if len(arg) > 1 and arg[0] == arg[-1] and arg[0] in quote_chars:
        arg = arg[1:-1]
    return arg