You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Dennis Hall from Los Angeles. Can you please help me with flight ticket booking to reach Washington?

ASSISTANT: Sure, I am happy to aid you in flight ticket booking process. Can you please let me know your preferable travel dates for booking flight ticket?

USER: Sure, I have planned my travel dates as 03/18 and 03/20.

ASSISTANT: May I know your airport codes?

USER: Sure, I would like to travel from LAX to IAD as these are very much familiar to me.

ASSISTANT: Please wait for a moment.

USER: Sure, take your time.

ASSISTANT: Sorry to say, no flight is available for you as per your requests.

USER: Oh! It is sad to hear. I need to choose another agency this time.

ASSISTANT: Thank you for reaching us, have a nice day.

USER: Anyway, thank you for your time.