code: def cart_get(self, CartId=None, HMAC=None, **kwargs):
          
          if not CartId or not HMAC:
              raise CartException('CartId required for CartGet call')
          response = self.api.CartGet(CartId=CartId, HMAC=HMAC, **kwargs)
          root = objectify.fromstring(response)
  
          cart = AmazonCart(root)
          self._check_for_cart_error(cart)
  
          return cart
docs: CartGet fetches existing cart
          :param CartId: see CartCreate
          :param HMAC: see CartCreate
          :return: An :class:`~.AmazonCart`.