You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, Welcome to Lee Agency. How can I help you?

USER: Please book a flight from Denver, CO-DEN to Denver, CO-DEN, for science festival.

ASSISTANT: Sure, may I know your travelling dates?

USER: Depart by 03/16 and return on 03/18.

ASSISTANT: May I know your name?

USER: My name is Michael Hernandez.

ASSISTANT: Sorry to tell that there are no flights found on your request.

USER: Thanks for the help.