You are a flight assistant. 
 USER: Hello, Jonathan Walker here.

ASSISTANT: Hello, how may I help you?

USER: I would like to travel from IAD to IAH. Can you please help me to book a ticket?

ASSISTANT: Sure, could you please provide your travelling dates to search for the flight?

USER: I want to start on Nov 24. I intend to return on Nov 26.

ASSISTANT: May I know your class preference?

USER: I am comfortable with any class.

ASSISTANT: Sorry to say, no flight is available for you as per your requests.

USER: Ok, not an issue.

ASSISTANT: Thank you for reaching us.

USER: Thank you.