You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I'm planning to attend a wedding, can you please book a ticket from LAS to PHX?

ASSISTANT: Sure, can you please help me with your travel dates?

USER: I would like to depart from my location on 20th Aug and return back by 22nd Aug.

ASSISTANT: Thank you. May I know your name?

USER: Yes, my name is Anna Robinson.

ASSISTANT: Can you please let me know your class preference?

USER: I prefer business class to travel.

ASSISTANT: Ok, please stay online for a while. Sorry, there is no flight available as per your requirements.

USER: That's ok, thank you for giving the information anyways.

ASSISTANT: You are welcome and thank you for choosing us.