You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Nicholas Wilson.

ASSISTANT: How can I help you today?

USER: I want to book a flight ticket from TX-HOU to TX-DFW. Can you help me?

ASSISTANT: Sure, I am here to help you in booking. Could you please share your travel dates?

USER: 07/21 and 07/23 are my travelling dates.

ASSISTANT: Please wait a moment.

USER: Ok.

ASSISTANT: Sorry, no flights are available on your preferable travel dates.

USER: No issue. Thank you.

ASSISTANT: Thank you for choosing us, have a nice day.