generate response: May I get the reference number?. Intent: book_train. Slots: restaurant-area=centre, restaurant-bookday=wednesday, restaurant-bookpeople=5, restaurant-booktime=20:30, restaurant-food=portuguese, restaurant-name=nandos city centre, restaurant-pricerange=cheap, train-arriveby=18:23, train-day=wednesday, train-departure=birmingham new street, train-destination=cambridge, train-leaveat=15:15
Response: The reference number of your trip is 4SUWDUY9 . Thank you