You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Brian Lopez.

ASSISTANT: How may I assist you today?

USER: I want to attend a wedding in New York. Can you book a flight ticket from OAK to LGA?

ASSISTANT: Sure Lopez, can you mention your travel dates?

USER: I want to travel in the flight on 12/21 and 12/23.

ASSISTANT: Sorry, I could not find any flight with your travel dates.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: My pleasure.