You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I am Donald Campbell. Can you help me in booking on 07/06 to 07/08, as there is a farewell party in my college?

ASSISTANT: May I know your desired airport codes please?

USER: My source is DCA and destination is ORD.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: No issue, thank you.

ASSISTANT: Thank you for opting us.