parser for MONO [8] issue mode
    MONO = 0x08; // All card transaction amounts are equal to 1

def mono_parser(cards: list) -> Optional[list]:
    '''
    parser for MONO [8] issue mode
    MONO = 0x08; // All card transaction amounts are equal to 1
    '''
    from pypeerassets.pautils import exponent_to_amount, amount_to_exponent

    processed_cards = []
    decimals = cards[0].number_of_decimals

    for c in cards:
        c.amount = [amount_to_exponent(
                     exponent_to_amount(c.amount[0], decimals),
                     decimals)]
        processed_cards.append(c)

    return processed_cards