You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello,. How can I serve you today?

USER: I am Jonathan Thomas,I want to book a flight ticket from Dallas, TX- DFW, to Chicago, IL - ORD.

ASSISTANT: May I know your travelling dates?

USER: Sure, I need the booking to be done on Feb 17th as depart date and Feb 19th as return date.

ASSISTANT: Based on your information there is no flight found.

USER: OK, that's fine. Thank you for the details.

ASSISTANT: Thank you for choosing us.