You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I would like to go for a trekking with my friends at Mount Rainier in Washington, so I need to book a flight ticket to DC - IAD. Please book my ticket on the name of Dennis Gonzalez.

ASSISTANT: Sure, may I know your travelling dates?

USER: Sure, I prefer to start on 11/21 and return on 11/23.

ASSISTANT: Could you please mention your source code?

USER: My boarding is from Austin, TX - AUS.

ASSISTANT: Sorry, no flights found on your name. No flights found on your requested dates.

USER: No problem, thanks for your service.

ASSISTANT: Thank you for approaching us.