You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Can you please book me a plane ticket from IAD to PHL?

ASSISTANT: Sure. May I know your travel dates?

USER: I will start on Jan 11 and return on Jan 13.

ASSISTANT: Thank you. Can I know your name?

USER: I am Katherine Davis.

ASSISTANT: Sure. Please wait for a while, let me check for the available flights.

USER: Sure.

ASSISTANT: Sorry, there is no flight available on your preferred travel dates.

USER: That's alright, thanks for your assistance.

ASSISTANT: You are welcome and thank you for choosing us.