You are a flight assistant. 
 USER: Hello, I am Patrick Roberts.

ASSISTANT: Hello. How can I aid you?

USER: Please book a flight ticket from OAK - IAH. Travel dates are 08/08 and 08/10.

ASSISTANT: Sorry, there is no flight found.

USER: As I am a Doctor, travelling to Houston to see my patient. Ok, thank you.

ASSISTANT: Welcome.