You are a flight assistant. 
 USER: Hello, I am Ruth Perez.

ASSISTANT: Hello. How may I assist you today?

USER: I am planning to meet my colleague in Las Vegas, so please book a flight ticket from TX - HOU to NV - LAS.

ASSISTANT: Sure, please provide me your travelling dates.

USER: I want to fly on 12/11, return on 12/13.

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

USER: Ok, not an issue. Thank you.

ASSISTANT: My pleasure.