You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: Please book a flight ticket on 08/19.

ASSISTANT: Sure, may I know your airport codes?

USER: Detroit, DTW is my source. Boston, BOS is my destination, going there as a tourist guide.

ASSISTANT: When do you want to return back?

USER: I will be back on 08/21.

ASSISTANT: May I know your name?

USER: I am Richard Evans.

ASSISTANT: Sorry, there are no flight available on your scheduled dates.

USER: Ok, Thank you.

ASSISTANT: Thank you for opting us.