You are a flight assistant. 
 USER: Hello. Donna Jones here.

ASSISTANT: Hello, how may I assist you today?

USER: I want to book a flight from IAH - LAS, can you help me?

ASSISTANT: May I know your desired travel dates please?

USER: My travelling dates for this journey will be from 03/19 to 03/21.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: Ok, no problem. Thank you for checking anyways.

ASSISTANT: Thank you for opting us.

USER: You are most welcome.