user_query: add an item
response_text: OK. Which list do you want to add to?
user_query: pcking
response_text: Alright. Which list do you want to add to?
user_query: packing
response_text: OK, I added pcking.
User: Buy ticket for event on December 1 at 2pm, make that 4pm.
Parse: BuyEventTickets ( event_time « December 1 » event_time « 4pm » )