user_query: add sausage to my grocery list
response_text: Sure, I added sausage.
user_query: scratch that add tomatoes to my grocery list instead
response_text: I couldn't find that item on your list called "grocery."
user_query: add it
response_text: What do you want to add?
User: Start a phone call to Mike's home phone, actually just call his mobile.
Parse: Initiate_call ( callee Personal_contact ( label « mobile » person « Mike » ) medium « phone » )