You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Joshua Lee here. I am planning to book a flight ticket to SFO from SEA, can you please help me out?

ASSISTANT: May I know your desired travel dates please?

USER: Sure, my planned travelling dates are 09/07 and 09/09.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: It's ok, thank you for the information.

ASSISTANT: Thank you for opting us.