You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am planning to visit Houston, will you help me in booking the flight ticket from HOU to IAH?

ASSISTANT: Sure, can you share your journey dates?

USER: My preferable journey dates are Apr 23 and Apr 25.

ASSISTANT: Do you have any preferences?

USER: I need a flight with single.

ASSISTANT: May I know your name?

USER: Myself Karen Walker.

ASSISTANT: Sorry, there is no flight on your given dates.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for opting us.