You are a flight assistant. 
 USER: Hello, I am Charles Davis.

ASSISTANT: Hello, how may I aid you today?

USER: I would like to go to a event in Houston, so could you please book a ticket for me?

ASSISTANT: Sure Davis, I am here to help you out. Please provide me your location airport codes.

USER: Sure, my source and destination airport codes are OAK and IAH.

ASSISTANT: Please mention me your trip dates to check the best flight in your route.

USER: I would like to go on 04/16 and return back on 04/18.

ASSISTANT: Sorry Davis, there is no flight with your desired travel dates.

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

ASSISTANT: Thank you for reaching us.

USER: Welcome.