You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you out?

USER: I am Sarah Smith from Seattle. I would like to go to Boston next week, can you please book a flight ticket for me?

ASSISTANT: Sure, I will help you out.

USER: Thanks.

ASSISTANT: May I know your travelling dates please?

USER: I want to take off on 09/18 and book my return ticket also on 09/20.

ASSISTANT: Can I know your airport codes please?

USER: I want to fly from SEA and destination airport is BOS.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Sorry, there are no flights found in our database.

USER: Oh! It's ok no problem. Thank you for your service.

ASSISTANT: Thank you for choosing us.