(card_one, card_two)
:param card_one: str - first card in hand.
    :param card_two: str - second card in hand.
    :return: bool - if the hand is a blackjack (two cards worth 21).
def is_blackjack(card_one, card_two):
    """

    :param card_one: str - first card in hand.
    :param card_two: str - second card in hand.
    :return: bool - if the hand is a blackjack (two cards worth 21).
    """

    pass
def is_blackjack ( card_one , card_two ) : pass