If your going to Cambridge, I have 5 trains running. Do you have a particular time?
I would like to book a train that leaves from Broxbourne on Wednesday. Can you book that for me? Yes, I need to leave sometimes after 11:30.
{"__type": "Inform", "entity": {"__type": "Train", "choice": "5", "destination": "Cambridge"}} {"__type": "Request", "service": "train", "values": ["leave at"]}
{"__type": "Inform", "entity": {"__type": "Train", "choice": "13"}} {"__type": "Request", "service": "train", "values": ["arrive by"]}
There are 13 trains. When would you like to arrive by?