user_query: add socks to shopping list
response_text: OK, I added socks.
user_query: scratch that add handkerchief instead 
response_text: Sure, I changed the list item to handkerchief on your list called "shopping."
user_query: shopping list
response_text: You have three things on that list.
User: No no more Lyft please.
Parse: Cancel_ride ( provider « Lyft » )