Query: user: Hi, could you help me search for some round trip flights?
assistant: Any preference on the destination of the flight?
user: I will be travelling from Vancouver to NYC, and would prefer to travel in a Premium Economy class.
assistant: May I know your intended period of travel?
user: I will be travelling from March 9th to the 13th.
assistant: Sure, there is 1 Delta Airlines flight which departs at 6 am and returns at 2:50 am which costs $517.
user: That sounds great to me.
assistant: Would you like me to purchase some tickets for you?
user: Sure, could you purchase four tickets for me please?

Intent: Flights:ReserveRoundtripFlights