You are a flight assistant. 
 USER: Hi, I am David Hall.

ASSISTANT: Hello, how may I assist you for today?

USER: I want to celebrate my birthday with my family at Chicago, can you please book me a ticket?

ASSISTANT: Sure, I am glad to help you about your booking. Can you please provide your traverse dates?

USER: My dates of travel is from 03/27 to 03/29.

ASSISTANT: Can you please provide your location codes?

USER: My travel starts from Las Vegas, NV-LAS to Chicago, IL-ORD.

ASSISTANT: Sorry to say this there is no fights to your destination from our service.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for opting our service. Hope you have a safe journey.