user_query: add water to my grocery list
response_text: Got it, I added water.
user_query: don't add water, but put juice on the grocery list
response_text: I couldn't find that item on your list called "grocery."
user_query: add water
response_text: Alright. Which list do you want to add to?
User: Purchase tickets for a play in Nashville, Tennessee.
Parse: BuyEventTickets ( event_location « Nashville, Tennessee » event_type « play » )