You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I am Paul Green. I would like to meet my father on his birthday, can you please help me to book my flight ticket from IAD to LAX?

ASSISTANT: Sure, May I know your travelling dates?

USER: Sure, I would like to depart on Sept 23 and I will return back on Sept 25.

ASSISTANT: Do you have any preferences?

USER: Yes, I prefer for a business class.

ASSISTANT: Thanks for your details.

USER: Please check for the single connection flight.

ASSISTANT: There are no flights found under business class.

USER: Sad to hear that. Anyway, thank you for checking.

ASSISTANT: Thank you.