You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Joseph White here.

ASSISTANT: How can I assist you at this moment?

USER: Actually, I am looking for a flight having with single stop over, can you please help me out with booking of a flight ticket?

ASSISTANT: Sure, I will help you in booking flight ticket.

USER: Thank you.

ASSISTANT: Could you please mention your travel dates for booking flight ticket?

USER: Sure, I am planning to move on 01/20 and please book my return ticket on 01/22.

ASSISTANT: May I know your preferable airport code names for further process?

USER: Sure, I want to travel from DCA to. My destination airport code is DFW.

ASSISTANT: Please hold on a moment, I will check flight availability in this route.

USER: Sure, take your time.

ASSISTANT: Sorry for the inconvenience no flights available in this route as per your requested dates.

USER: Oh! So sad to hear. Anyway, I will choose another alternative to go there. Thank you for the information.

ASSISTANT: Thank you for reaching us, have a good day.

USER: Welcome.