You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what kind of assistance are you looking for?

USER: I am Debra Davis. Please book a flight ticket from Los Angeles, LAX to Las Vegas, LAS.

ASSISTANT: Sure, I can book a flight ticket for you.

USER: Thank you.

ASSISTANT: May I know on which dates you want me to book flight ticket?

USER: Sure, My travelling dates are from 12/20 to 12/22.

ASSISTANT: Sorry, no flights are available on your desired routes.

USER: Ok, No issues. Thank you.

ASSISTANT: Thanks for contacting us, hope to serve you better next time.