user_query: Add mango, apple and banana to my Fruits list.
response_text: I couldn't find a list called "Fruits." Do you want me to make one?
user_query: Remove apple.
response_text: No problem, nothing's been changed.
User: Can I get a PDF of my Walmart credit card bill?
Parse: Get_bill ( account_provider « Walmart » account_type « credit card » document_format « PDF » )