You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I serve you today?

USER: I am Mary Lee.

ASSISTANT: Ok.

USER: I want to change my reservation which was booked for Houston, can you please modify it?

ASSISTANT: Sure Lee, please wait for a while.

USER: Ok.

ASSISTANT: Sorry Mary Lee, no reservation is done previously in our data list.

USER: Ok, thank you for informing me.

ASSISTANT: Thank you for approaching us.