You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I am Kimberly Nelson. Please book a flight ticket on dates 03/25 and 03/27.

ASSISTANT: May I know your desired airport codes please?

USER: My airport codes are OAK and LAX.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: That's ok. Thank you for the response.

ASSISTANT: Thank you for opting us.