i need a train departing from cambridge . i will be going to london liverpool street on sunday .
ok , where will you be going ?
{'service': 'train', 'act': 'inform', 'slot_name': 'day', 'value': 'saturday'} {'service': 'train', 'act': 'request', 'slot_name': 'leave', 'value': '?'} {'service': 'train', 'act': 'request', 'slot_name': 'arrive', 'value': '?'}
and what time would you like to leave after or arrive by on saturday ?