i am looking for a train departing from london kings cross yes departing from there heading to cambridge on saturday .
when would you like to depart london kings cross ?
{'service': 'train', 'act': 'request', 'slot_name': 'leave', 'value': '?'} {'service': 'train', 'act': 'request', 'slot_name': 'arrive', 'value': '?'}
what time would you like to depart or arrive ?