facade pattern @staticmethod def make_invoice(customer_id)return invoice(customer fetch(customer_id)@staticmethod def make_customer()return customer(@staticmethod def make_item(item_barcode)return item(item_barcode@staticmethod def make_invoice_line(item)return invoiceline(item@staticmethod def make_receipt(invoicepayment_type)return receipt(invoicepayment_type@staticmethod def make_loyalty_account(customer)return loyaltyaccount(customer@staticmethod def fetch_invoice(invoice_id)return invoice(customer@staticmethod def fetch_customer(customer_id)return customer(customer_id@staticmethod def fetch_item(item_barcode)return item(item_barcode@staticmethod def fetch_invoice_line(line_item_id)return invoiceline(item