You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I guide you?

USER: Jason Thomas here. Can you book me a ticket from IAD to JFK?

ASSISTANT: Ok, can I know your preferable dates?

USER: Ok. I would like to travel on 03/21 and 03/23.

ASSISTANT: I am sorry, there are no available flights.

USER: No issues, thank you for your time.

ASSISTANT: Thank you, have a good day.