user_query: add cheese to grocery list
response_text: OK, I added cheese.
user_query: Nevermind take that off
response_text: Are you sure you want to go ahead and delete it?
user_query: yes
response_text: Sure, I deleted the list called "grocery."
User: Start tracking a 30 minute walk
Parse: Start_exercise ( activity « walk » duration « 30 minute » )