You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: Can you please book a ticket from DTW to IAD to go for shopping?

ASSISTANT: Sure, I am here to help you with that. Can I know your planned trip dates?

USER: My travelling dates are July 19 and July 21.

ASSISTANT: Do you have any other requirements?

USER: I prefer business class.

ASSISTANT: Ok, may I know your name?

USER: Sure, I am Joshua Evans.

ASSISTANT: Ok, wait for a minute.

USER: Ok.

ASSISTANT: Sorry to say that, there are no flight's available based on your travelling dates.

USER: Ok, Thank you.

ASSISTANT: Thank you for approaching us.