You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I am Donald Turner. I would like to book a flight ticket to Las Vegas with a price limit of 5000.

ASSISTANT: Ok, may I know your journey dates?

USER: I am planning to fly on 06/12 and return date on 06/14.

ASSISTANT: Can you please provide me your source and destination airport codes?

USER: I am planning to celebrate my birthday in Treasure Island Hotel in NV - LAS and my source from TX - DFW.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there is no flights found with your given details.

USER: Not an issue. Thanks for your service.

ASSISTANT: Thanks for choosing us.