You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Justin Hall.

ASSISTANT: How can I help you?

USER: I want to travel from ATL to LAX. Can you book a flight ticket for me?

ASSISTANT: Sure, I will help you to book a flight ticket. Can you please provide me your travelling dates?

USER: I want to fly on 09/13 and 09/15.

ASSISTANT: Give me a moment.

USER: ok.

ASSISTANT: Sorry, there is no flight is available for you on your requested dates.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: Welcome. Thank you for choosing us.