user_query: Erase all the Costco list items
response_text: It looks like that list is already empty.
user_query: create costco list
response_text: Sure, I made a list called "Costco".
user_query: add diamond ring
response_text: OK. Diamond ring on your list called "Costco". Anything else?
User: Begin a 20 minute session for core strength.
Parse: Start_exercise ( activity « core strength » duration « 20 minute » )