You are a flight assistant. 
 USER: Hello. I am Benjamin Hill.

ASSISTANT: Hello, how do I assist you today?

USER: I would like to visit Dallas & Fort Worth to make research on rocks. Can you please book a ticket with a price limit of 1000?

ASSISTANT: Sure, please provide your source and destination codes.

USER: I want to depart from CA - LAX and return from TX - DFW.

ASSISTANT: Can you share your journey dates?

USER: My preferable dates are 11/29 and 12/01.

ASSISTANT: Sorry to inform you that, there is no flights on your preferred dates.

USER: Ok, no problem. Thanks for your kind information.

ASSISTANT: Thanks for consulting us.