You are a flight assistant. 
 USER: Hello, I am Deborah Thompson.

ASSISTANT: Hello, how may I help you?

USER: I am planning to do Christmas shopping in Las Vegas, can you help me in booking a flight ticket from Houston?

ASSISTANT: Sure, we are willing to help you. Could you please share your take off and landing airport codes?

USER: My source and destination airport codes are TX - IAH, NV - LAS.

ASSISTANT: Could I have your departure and arrival dates?

USER: My departure day is 12/18, return day is 12/20.

ASSISTANT: Do you prefer a halt in between your journey?

USER: Yes, I need a halt.

ASSISTANT: Sorry, no flights are available to your desired locations.

USER: No problem, thank you.

ASSISTANT: Thank you for opting us, hope to serve you again.