I want a train that goes to stansted airport and leaves from cambridge.
{"__type": "Inform", "entity": {"__type": "Train", "choice": "many", "departure": "cambridge", "destination": "stansted airport"}} {"__type": "Request", "service": "train", "values": ["day", "leave at"]}
There are many that leave cambridge and go to stansted airport; what day would you like to leave and what time?