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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def print_model(self):
 """Return the assembled cards as a JSON string. Returns ------- cards_json : str The JSON string representing the assembled cards. """

        cards = [c.card for c in self.cards]
        # If there is only one card, print it as a single
        # card not as a list
        if len(cards) == 1:
            cards = cards[0]
        cards_json = json.dumps(cards, indent=1)
        return cards_json