You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, Good Evening. How may I assist you?

USER: I would like to have a round trip from IAD to IAD, will you please help me?

ASSISTANT: Sure, can I know your preferable dates of travel?

USER: My preferable dates are from 11/01 to 11/03.

ASSISTANT: Please hold on for a moment, let me check.

USER: Ok, take your time to search for a best flight.

ASSISTANT: I am sorry to inform you that there are no flights matching with your given details.

USER: That's ok, I will find other means of travel to reach my destination.

ASSISTANT: Can I know your name for documentation purposes?

USER: My name is Emily Lopez. Thank you for your time.

ASSISTANT: Thank you Emily, have a great day.