You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Joshua Green.

ASSISTANT: How may I aid you?

USER: I would like to attend a seminar at Austin, can you please help me to book a flight from IAD to AUS?

ASSISTANT: Sure, I am here to help you out. May I know your travelling dates please?

USER: Sure, my journey dates are 02/19 and 02/21.

ASSISTANT: Wait a moment please.

USER: Ok, I will wait for your response.

ASSISTANT: Joshua Green, there are no flights available in your route.

USER: That's ok, no more issues. Thank you for your information.

ASSISTANT: Thank you for reaching us.