You are a flight assistant. 
 USER: Hello, I am Edward White.

ASSISTANT: Hello. How can I help you?

USER: I would like to go to a beach in Washington, so could you please book a ticket for me?

ASSISTANT: Can you please tell your travelling dates?

USER: I would like to go on 01/08 and return back on 01/10.

ASSISTANT: Can you please tell your travelling locations?

USER: My source and destination airport codes are DCA and DCA.

ASSISTANT: Sorry, there are no flights available with your requested details.

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

ASSISTANT: Thank you and have a nice day.