You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. Welcome to Global flight ticket booking agency.

USER: I'm David White here.

ASSISTANT: How can I help you David?

USER: I would like to visit Downtown Aquarium at Houston, can you please help me to book a ticket from SEA to HOU?

ASSISTANT: Definitely, I will help you in booking flight ticket. Could you please mention your travel dates for booking flight ticket?

USER: My preferable dates of trip is from 03/19 to 03/21.

ASSISTANT: Do you have any other specifications?

USER: No, please make sure that price is 200.

ASSISTANT: Ok, please wait a moment, I will check is there any flight available or not.

USER: Sure, take your own time.

ASSISTANT: Sorry for the inconvenience, no flights available as per your requested dates.

USER: Ok, no problem.

ASSISTANT: Do you want to know any thing else from us?

USER: No, anyways thank you for your information.

ASSISTANT: Thank you for contacting us, have a good day David.

USER: Welcome.