You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Christine Harris. I have to attend a Live Concert at San Francisco, could you please help me with booking a flight ticket?

ASSISTANT: can I know your travel dates?

USER: I would like to take off on 10/15 and return on 10/17.

ASSISTANT: Please help me with your airport codes.

USER: My source airport code is DEN and destination airport code is SFO.

ASSISTANT: Please wait for a moment.

USER: Sure, take your time.

ASSISTANT: Sorry to say this, there is no reservation found basis on your details.

USER: That's ok, not an issue. Anyways, thank you for the information.

ASSISTANT: Most welcome.