You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I am planning to visit Los Angeles, can you please book me a ticket from PHL to LAX?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Can I have your travel dates please?

USER: My preferable journey dates are from 03/18 to 03/20.

ASSISTANT: Ok, please be hold on for a moment.

USER: Sure, take your own time.

ASSISTANT: Sorry to inform you that no flight is available to you on your dates.

USER: Ok, not an issue.

ASSISTANT: May I know your good name please for documentation purpose?

USER: My name is Donald Williams.

ASSISTANT: Ok, thank you for choosing us.

USER: Thank you for providing information.

ASSISTANT: Welcome.