You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you today?

USER: Sandra Taylor here.

ASSISTANT: Ok.

USER: I would like to book a ticket from DFW to IAD, can you please help me with that?

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

USER: The travel dates are from 12/10 to 12/12.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, no flights found on your requested travelling dates.

USER: No problem, thank you for your information.

ASSISTANT: Thank you for approaching us, have a nice day.