'If the card image is greater than 80 characters, it should consist of a
normal card followed by one or more CONTINUE card.  This method returns
the subcards that make up this logical card.'

def _itersubcards(self):

    ncards = (len(self._image) // Card.length)
    for idx in range(0, (Card.length * ncards), Card.length):
        card = Card.fromstring(self._image[idx:(idx + Card.length)])
        if ((idx > 0) and (card.keyword.upper() != 'CONTINUE')):
            raise VerifyError('Long    card    images    must    have    CONTINUE    cards    after    the    first    card.')
        if (not isinstance(card.value, str)):
            raise VerifyError('CONTINUE    cards    must    have    string    values.')
        (yield card)
