You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Kathleen Thompson here. I want to visit Denver zoo with my family, so please book my ticket from Phoenix.

ASSISTANT: Sure Kathleen, I will help you with that. Please mention your travel dates.

USER: My itinerary dates are 09/02 and 09/04.

ASSISTANT: May I know your airport codes please?

USER: My genesis and terminus airport codes are PHX and DEN.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: I am sorry to inform you that there is no flight available at your requested dates.

USER: No problem, thank you.

ASSISTANT: Thank you for choosing us.