design pattern quick reference @dummy_decorator def do_nothing()print("inside do_nothing"if __name__ ="__main__"print("wrapped function",do_nothing __name__do_nothing(facade simple_ facade py class invoicedef __init__(selfcustomer)pass class customeraltered customer class to try to fetch customer on init or creates new one def __init__(selfcustomer_id)pass class itemaltered item class to try to fetch an item on init or creates new one def __init__(selfitem_barcode)pass class facade@staticmethod def make_invoice(customer)return invoice(customer@staticmethod def make_customer(customer_id)return customer(customer_id@staticmethod def make_item(item_barcode)return item(item_barcode