You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: Stephanie Martinez here. I would like to travel to Houston Zoo and I want a direct flight, can you please help me with that?

ASSISTANT: Sure, when are you travelling to Houston?

USER: The travelling dates are from 02/29 to 03/02.

ASSISTANT: Please share your airport codes?

USER: The source airport code is PHX and destination airport code is IAH.

ASSISTANT: There is no flight available on your route.

USER: That's fine, thank you for your help.

ASSISTANT: You are welcome.