generate response: What is the reference number for that reservation?. Intent: book_restaurant. Slots: restaurant-area=centre, restaurant-bookpeople=4, restaurant-booktime=17:00, restaurant-food=portuguese, restaurant-name=nandos city centre, restaurant-pricerange=cheap
Response: Booking was successful. The table will be reserved for 15 minutes. Reference number is : WS5P73O7 .