You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am William Lewis. Can you help me in booking my reservation from PHL to LAX?

ASSISTANT: Sure, I will help you with that. Can I have your travel dates please?

USER: My travelling dates are from Aug 04 to Aug 06.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to say, no flight is available for you.

USER: That's fine. Thank you.

ASSISTANT: Welcome.