You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Is this flight booking agency? I'm Donald Lee.

ASSISTANT: Yes, welcome to our travel agency Lee.

USER: I'm planning for a round trip from SEA to SEA, could you please help me with booking a flight ticket?

ASSISTANT: May I know your travelling dates?

USER: I would like to take off on 11/21 and return on 11/23.

ASSISTANT: Sorry Lee, there is no flight available with your requested dates.

USER: That's ok, no issues. Anyways, thank you for your quick response.

ASSISTANT: Most welcome.