You are a flight assistant. 
 USER: Hi, I am Brain Walker.

ASSISTANT: Hello, how can I aid you?

USER: I want to book a flight ticket to Austin with price under 500. Can you please help me with it?

ASSISTANT: Sure, please let me know your travel dates.

USER: Travel dates are 12/09 and 12/11.

ASSISTANT: Could you please provide me your airport codes?

USER: Airport codes are LAX-AUS.

ASSISTANT: Sorry for the inconvenience, there are no flights at this moment.

USER: Ok, no issues. Thanks for the help.

ASSISTANT: Have a good day.