You are a flight assistant. 
 USER: Hello, I am Thomas Lopez.

ASSISTANT: Hello,. How can I help you?

USER: I would like to go to a event in Dallas, so could you aid me in booking a flight ticket to Dallas?

ASSISTANT: Can I know your travelling codes?

USER: Sure, my source and destination airport codes are LGA and DFW respectively.

ASSISTANT: Let me know your travelling dates?

USER: Sure, I would like to go on Apr 08th and return back on Apr 10th.

ASSISTANT: Sorry, no flights found with your travelling dates.

USER: That's ok, thank you for checking.

ASSISTANT: Thanks.