code: def retrieve(payment, refund_id):
          
          if isinstance(payment, resources.Payment):
              payment = payment.id
  
          http_client = HttpClient()
          response, _ = http_client.get(routes.url(routes.REFUND_RESOURCE, resource_id=refund_id, payment_id=payment))
          return resources.Refund(**response)
docs: Retrieve a refund from a payment and the refund id.
  
          :param payment: The payment id or the payment object
          :type payment: resources.Payment|string
          :param refund_id: The refund id
          :type refund_id: string
  
          :return: The refund resource
          :rtype: resources.Refund