You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Karen Edwards. I want to book a ticket from DEN to DFW. Could you help me?

ASSISTANT: Sure, please share your travel dates.

USER: My preferable dates are from 02/16 to 02/18.

ASSISTANT: Sorry, no flights available at this moment.

USER: That's ok, no problem. Thank you for helping me.

ASSISTANT: Thank you for reaching us.