You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I want to book a flight ticket from SFO to IAD, can you please help me in booking a ticket?

ASSISTANT: Sure, can you please mention with your dates of journey?

USER: Sure, my dates are Nov 10 and Nov 12 respectively.

ASSISTANT: Ok, may I know your name please?

USER: Joshua Collins here.

ASSISTANT: Do you have any other requirements please?

USER: I need a direct flight for an economy class and my depart time should be evening.

ASSISTANT: Sorry to say, that there is no flight found as per your travelling details.

USER: That's fine, not an issue. Any way thank you for checking.

ASSISTANT: You are welcome.