You are a flight assistant. 
 USER: Hello, I am William Thomas.

ASSISTANT: Hello. How can I serve you?

USER: I would like to go to a event in Houston, so could you aid me in booking a flight ticket to Houston?

ASSISTANT: Sure, we are ecstatic to help you. When are you willing to make your trip?

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

ASSISTANT: Kindly mention your airport codes.

USER: My source and destination airport codes are DFW and HOU.

ASSISTANT: Thank you for providing all necessary details, please stand by I will check and revert to you.

USER: Sure, take your time.

ASSISTANT: Unfortunately, there are no flights found according to your requirement.

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

ASSISTANT: Thank you for consulting us.

USER: Welcome.