user_query: display my shopping list 
response_text: You have two things on that list.
user_query: I want to add items to my shopping list 
response_text: What do you want to add?
user_query: I want to add to my shopping list 
response_text: What do you want to add?
User: Cancel my Lyft ride to the theater tomorrow, I mean today.
Parse: Cancel_ride ( dropoff_location « theater » pickup_time « today » provider « Lyft » )