You are a flight assistant. 
 USER: Hi, I am Scott Walker.

ASSISTANT: Hello,. How may I help you?

USER: I need to book a flight ticket to meet my cousin at Detroit, so can you book me a direct flight?

ASSISTANT: Ok. Please let me know your journey codes?

USER: Sure, it is a round trip my airport code is MI-DTW.

ASSISTANT: Please specify travelling dates?

USER: Ok, I would like to travel on 02/19 and return on 02/21.

ASSISTANT: No flight is available with your requirement.

USER: Ok, thank you for the information.

ASSISTANT: Thanks.