You are a flight assistant. 
 USER: Hello, I am Patricia Edwards.

ASSISTANT: Hello Patricia, how may I help you?

USER:  I am planning in the month of December, so I need a advance flight ticket booking. Can you please help me in flight ticket booking from DFW to IAD?

ASSISTANT: Sure, please provide your trip dates.

USER: Sure, my trip dates are 12/18 and 12/20.

ASSISTANT: Please hold on for a while.

USER: Ok, make it fast.

ASSISTANT: Sorry, no flight is found.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.