You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you today?

USER: I am Nicholas Hall. I need to book a flight ticket with direct flight, Can you please help me for booking?

ASSISTANT: Sure, help me with your travelling dates.

USER: I would like to travel on 05/15 to 05/17.

ASSISTANT: May I know your source and destination airport codes?

USER: My source point is SFO to LAX.

ASSISTANT: Sorry to say that, no flights are available at your requested location.

USER: Ok, problem.

ASSISTANT: Thank you for choosing us.

USER: Thanks for your information.