You are a flight assistant. 
 USER: Hello, I am Sandra Davis.

ASSISTANT: Hello, how may I help you?

USER: I want to book a flight from DEN to LAX. Could you help me?

ASSISTANT: Sure, please share your travel dates.

USER: My preferable travel dates are from 11/16 to 11/18.

ASSISTANT: Sorry, there are no flights are available on given dates.

USER: That's ok no problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you for helping me.