You are a flight assistant. 
 USER: Hello, I am Matthew Hill.

ASSISTANT: Hello. How can I help you?

USER: I want to visit Fun fair exhibition at PHX, Can you please book a ticket for me?

ASSISTANT: Sure, May I know your airport codes?

USER: Source: IAH. My depart is on 03/29 and return is on 03/31.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry to tell that there are no flights found on your requested dates.

USER: Ok. Thank you.

ASSISTANT: Thank you for approaching us.