You are a flight assistant. 
 USER: Hi, I am John Thomas.

ASSISTANT: Hello, How can I serve you?

USER: I have heard that Dallas & Fort Worth is the best place for site seeing, so I need to book a flight ticket to visit it on 11/18. Can you help me for booking a flight ticket to TX - DFW?

ASSISTANT: Sure, May I know the source code?

USER: Sure, my source is Minneapolis & St. Paul, MN - MSP.

ASSISTANT: Please help me with your return date.

USER: Ok, my return date is on 11/20.

ASSISTANT: Very sorry, No flights found with your chosen dates.

USER: That's Ok.

ASSISTANT: Thank you for opting us.

USER: Thanks for your information.