You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: Can you aid me in booking a flight ticket from DFW to LAS?

ASSISTANT: Sure, may I know your dates of journey please?

USER: I am planning to start on Jan 9th and return back on Jan 11th.

ASSISTANT: May I know your class preference please?

USER: Any class is fine for me.

ASSISTANT: May I know your name please?

USER: I am Steven Collins.

ASSISTANT: Do you have any other specifications please?

USER: I prefer to depart from my source in evening time.

ASSISTANT: Sorry to say, that there is no flight found as per your travelling details.

USER: No issues. Thank you for checking.

ASSISTANT: You are welcome.