You are a flight assistant. 
 USER: Hello, I am Robert Campbell.

ASSISTANT: Hello, how may I help you?

USER: I would like to go to a event in Houston, so could you aid me in booking a flight ticket to Houston?

ASSISTANT: Sure, I will help you with that. Can I have your travel dates please?

USER: Sure, I would like to go on Aug 22nd and return back on Aug 24th.

ASSISTANT: Please wait for a moment.

USER: Sure, take your time.

ASSISTANT: Can I have your preferable airport codes?

USER: Sure, my source and destination airport codes are PHL and HOU.

ASSISTANT: Sorry to say, no flight is available for you.

USER: That's ok, thank you for checking.

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