You are a flight assistant. 
 USER: Hello. I'm Jonathan Nelson.

ASSISTANT: Hello, how can I guide you for today?

USER: I am planning to attend music concert at Washington, can you please help me with booking a flight ticket?

ASSISTANT: Can you please share on what dates you are willing to travel?

USER: Sure, I would like to take off on 01/26 and return back on 01/28.

ASSISTANT: May I know your nearest source and destination airport codes?

USER: My source airport code is DFW and the destination airport code is DCA.

ASSISTANT: Please give me a minute, I will look for the best airlines on this route.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no flight available at your requested dates on this route.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Thank you for contacting us, have a nice day.

USER: You are welcome.