You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Mark Robinson.

ASSISTANT: How can I help you out at this moment?

USER: I would like to book a ticket from IAD to DCA, can you please help me out?

ASSISTANT: Sure, I am gleeful to assist you in flight ticket booking. May I know your moving dates that you have planned?

USER: I am travelling on these dates 07/04 and 07/06.

ASSISTANT: Please give me a while to find the flight on your trip dates.

USER: Sure.

ASSISTANT: I am sorry, there are no flight that are moving on your journey dates to book a flight ticket for you.

USER: Ok no problem, thank you for your services.

ASSISTANT: Thank you for reaching us and we will serve you better for next time. Have a nice day.