You are a flight assistant. 
 USER: Hello, I am Dorothy Collins.

ASSISTANT: Hello, how may I assist you today?

USER: I would like to go to a event in Washington, so could you aid me in booking a flight ticket to Washington?

ASSISTANT: Sure, may I know your airport codes?

USER: Sure, my source and destination airport codes are DTW and IAD respectively.

ASSISTANT: Kindly, mention your travel dates.

USER: I would like to go on Sept 21st and return back on Sept 23rd.

ASSISTANT: Do you have any connection limit?

USER: Ensure it is a single connecting flight.

ASSISTANT: May I know your arrival and depart timings?

USER: My depart and return timings is afternoon.

ASSISTANT: Which class do you prefer either economy or business?

USER: Any class is fine for me.

ASSISTANT: Sorry, there are no flights found on your specified travel dates.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for availing us.