i want to book a taxi . i want to leave from the train station . i want to leave london kings cross train station after 02:00
sure , i can help you with that . where will you be departing from ? can you tell me what time you would like to leave ?
{'service': 'taxi', 'act': 'request', 'slot_name': 'dest', 'value': '?'}
okay , and what is your destination ?