code: def print_model(self):
          
          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
docs: Return the assembled cards as a JSON string.
  
          Returns
          -------
          cards_json : str
              The JSON string representing the assembled cards.