You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Joshua Lewis.

ASSISTANT: How can I assist you?

USER: I am planning to book a ticket from DCA to BOS. Can you please help me out to book a ticket for me?

ASSISTANT: Sure Lewis, can I know the travel dates please?

USER: I would like to travel on 04/22 and return back on 04/24.

ASSISTANT: Ok, wait a moment please.

USER: Sure.

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

USER: That's fine.

ASSISTANT: Thank you for approaching us.

USER: Thank you for your service.