user_query: Email david@gmail.com 
response_text: Alright, you want to email david@gmail.com. What's the message?
user_query: Email David 
response_text: There's no email address listed for that contact.
user_query: Send email 
response_text: Who do you wanna email?
User: Buy tickets for the football game on Saturday.
Parse: BuyEventTickets ( event_time « Saturday » event_type « football game » )