You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I guide you for today?

USER: I am Sarah Harris want to visit Chicago, can you book a ticket from OAK to ORD?

ASSISTANT: Can you please share on what dates you are willing to travel?

USER: Sure, my travelling dates will be 12/19 and 12/21.

ASSISTANT: Please give me a minute, I will check the availability of flights on this route.

USER: Ok.

ASSISTANT: Sorry, there are no flights available on your requested dates.

USER: That's ok, thank you.

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