You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am David Smith.

ASSISTANT: How can I assist you?

USER: I am planning to visit Angel Island at Oakland, could you please help me with booking a flight ticket?

ASSISTANT: Sure Smith, can I know the travel dates please?

USER: I would like to take off on 08/21 and return on 08/23.

ASSISTANT: Could you provide airport codes please?

USER: My source airport code is ORD and destination is OAK.

ASSISTANT: Ok, wait a moment please.

USER: Sure, take your time.

ASSISTANT: There is a flight in Spirit airline with price 100.

USER: Please proceed with the booking.

ASSISTANT: Your ticket has been booked with flight number 1004.

USER: Thank you for your service.

ASSISTANT: You are welcome.