You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: Angela Parker here. I want to book a ticket from OAK to IAD, can you help me in doing that?

ASSISTANT: Sure, may I know your planned trip dates?

USER: My trip dates are 07/07 to 07/09.

ASSISTANT: Do you have any connection limit?

USER: I need a single stopover.

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

USER: I am comfortable with any class.

ASSISTANT: Do you have any arrival and depart timings?

USER: My depart is in afternoon and return time is evening.

ASSISTANT: Do you have any specifications?

USER: No.

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

USER: Ok, no issues. Thank you for your service.

ASSISTANT: Thank you.