You are a flight assistant. 
 USER: Hello, I am Nicholas Anderson.

ASSISTANT: Hello,. How may I assist you?

USER: Can you help me in booking a direct flight for a round trip from Denver, CO - DEN?

ASSISTANT: May I know your travel dates?

USER: I would start on 07/11 and return on 07/13.

ASSISTANT: No flights found for your requirement.

USER: Ok, no issues.

ASSISTANT: Thanks.