code: func CheckBillingOrderComplete(sess *session.Session, receipt *datatypes.Container_Product_Order_Receipt) (bool, *datatypes.Billing_Order_Item, error) {
  	return CheckBillingOrderStatus(sess, receipt, []string{"COMPLETE"})
  }
docs: // CheckBillingOrderComplete returns true if the status of the billing order for
  // the provided product order receipt is "COMPLETE". Returns false otherwise,
  // along with the billing order item used to check the statuses, and any error encountered.