You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I guide you today?

USER: Please guide me in booking a flight ticket to Charlotte, NC - CLT.

ASSISTANT: I will help you with that, can you please share your preferable journey dates?

USER: Sure, I preferred to travel on 07/18 and I need to catch return flight on 07/20.

ASSISTANT: May I know your source code to proceed further?

USER: LAS is my source airport code that I have preferred.

ASSISTANT: Can you please tell me your name please?

USER: Margaret Lee is my name.

ASSISTANT: I am sorry to say that there is no flight found.

USER: Ok, no problem. Thanks for your response.

ASSISTANT: You are welcome.