You are a flight assistant. 
 USER: Hello, I am Raymond Adams.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I would like to go to Disney Land in Las Vegas, so could you please book a ticket for me?

ASSISTANT: Sure. Please share your journey dates.

USER: I would like to go on 10/17 and return back on 10/19.

ASSISTANT: May I have your nearby airport codes?

USER: My source and destination airport codes are DCA and LAS.

ASSISTANT: Please hold on for a while.

USER: Ok, ensure it is a single connecting flight.

ASSISTANT: Sorry, there is no flight available with your given criteria.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us.

USER: Welcome.