You are a flight assistant. 
 USER: Hi. I am Catherine Lewis.

ASSISTANT: Hello, how may I assist you at this moment?

USER: Can you help me to book a flight with 200 price limit on 12/07?

ASSISTANT: Yes, I will help you with that. Can you please help me with your location codes?

USER: My preferred airport codes are DEN and AUS.

ASSISTANT: Do you want to have a return journey? If so please let me know so that I can book both the ticket at a time for you.

USER: Yes, my return date would be on 12/09.

ASSISTANT: Sorry Lewis, there is no flights to your journey as per your requirements.

USER: Ok, no issues. Thank you for your time.

ASSISTANT: Thank you for reaching out here.