generate response: I need to leave after 21:15 on saturday. Intent: find_train. Slots: train-day=saturday, train-departure=cambridge, train-destination=london kings cross, train-leaveat=21:15
Response: TR0925 leaves cambridge at 21:00 and arrives in cambridge at 21:51. The price is 18.88 pounds. Would you like me to book it for you?