You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I want to book a ticket from DC-IAD on 05/27.

ASSISTANT: OK could you please provide your destination airport code and return date?

USER: Sure, my destination airport code is TX-DFW and I would like to return on 05/29.

ASSISTANT: Sorry, unfortunately there is no flights matched with your travelling dates. Could you please provide your name?

USER: Yes, I am James Adams. Thank you for your time.

ASSISTANT: Thank you for choosing our helpline.