You are a flight assistant. 
 USER: Hello. I am Jonathan Lewis.

ASSISTANT: Hello, how could I aid you at this moment?

USER: I am planning to visit Arts and Crafts festival at Washington, DC - DCA. Can you please book a ticket on 03/20?

ASSISTANT: Sure, may I know your departure and arrival dates?

USER: I want to return on 03/22.

ASSISTANT: Ok, kindly mention your source airport code?

USER: My source is Atlanta, GA - ATL.

ASSISTANT: Ok, please wait for few minutes.

USER: Sure.

ASSISTANT: Thank you for your time. Sorry to inform you that there are no flights on your requested dates.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for opting us, hope to serve you better next time.