You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I help you?

USER: I am planning to celebrate my birthday at Denver, will you help me in booking the flight ticket on Dec 21?

ASSISTANT: Sure, May I know your source code?

USER: My source code is MSP.

ASSISTANT: When are you willing to coming back?

USER: There is a change in my depart day it is Dec 23 and I would like to return on Dec 25.

ASSISTANT: Do you have any preferences?

USER: No, thank you for asking.

ASSISTANT: You have a connecting flight 1001 in JetBlue airline and price 100, Shall I proceed?

USER: Sure you can proceed with the booking.

ASSISTANT: Your ticket has been reserved.

USER: Thank you for your help.

ASSISTANT: Thank you.