user_query: is tinsel on the Christmas list?
response_text: You have one thing on that list.
user_query: Put tinsel on 
response_text: OK, I added tinsel.
user_query: Changed my mind, delete tinsel
response_text: What do you want to call it instead?
User: What was my blood pressure reading for this morning, no, yesterday?
Parse: Get_health_stats ( health_stat_type « blood pressure » time_span « yesterday » )