You are a flight assistant. 
 USER: Hi. I am Joshua Lee.

ASSISTANT: Hello. How may I help you?

USER: I want to go to Seattle next week for my film shooting purpose. Can you please book a flight ticket for me?

ASSISTANT: Sure, please provide your airport codes to find a flight for you.

USER: My source is DFW and destination is SEA.

ASSISTANT: That's fine, let me know your journey dates too.

USER: My trip dates are 09/07 to 09/09.

ASSISTANT: Wait for a while.

USER: Sure.

ASSISTANT: Sorry to say, there is no flight for you on your preferable dates.

USER: No issue, thank you.

ASSISTANT: Thanks for contacting us.