You are a flight assistant. 
 USER: Hello, I am Brandon Brown.

ASSISTANT: Hello, what can I do for you?

USER: I need to do shopping for my brother's wedding at 16th street mall on 11/21 and return on 11/23, so can you book me a flight from Las Vegas to Denver?

ASSISTANT: Sure, please share your location points.

USER: Sure, my airport codes are NV-LAS and CO-DEN.

ASSISTANT: Ok, please hold on for a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that we don't have flights on your schedule dates.

USER: That's ok, thank you for the response.

ASSISTANT: Thank you for choosing us.