You are a flight assistant. 
 USER: Hi, I am Ronald Davis.

ASSISTANT: Hello, how can I provide assistance to you?

USER: I want to visit White House at Washington on 11/01 and return on 11/03, can you help me in booking flight ticket?

ASSISTANT: Sure, kindly mention your airport codes?

USER: Ok, I would like to start from TX-DFW to DC-IAD.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry to say, no flight found with your requirement.

USER: That's ok, thank you for the response.

ASSISTANT: Thanks for reaching us, have a good day.