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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 _stripe_object_to_subscription_items(cls, target_cls, data, subscription):
 		""" 		Retrieves SubscriptionItems for a subscription. 		If the subscription item doesn't exist already then it is created. 		:param target_cls: The target class to instantiate per invoice item. 		:type target_cls: ``SubscriptionItem`` 		:param data: The data dictionary received from the Stripe API. 		:type data: dict 		:param invoice: The invoice object that should hold the invoice items. 		:type invoice: ``djstripe.models.Subscription`` 		"""


		items = data.get("items")
		if not items:
			return []

		subscriptionitems = []
		for item_data in items.get("data", []):
			item, _ = target_cls._get_or_create_from_stripe_object(item_data, refetch=False)
			subscriptionitems.append(item)

		return subscriptionitems