You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Joseph Moore here.

ASSISTANT: How can I assist you?

USER: As I want to travel from HOU to IAD, can you please help me in booking a flight ticket?

ASSISTANT: Sure, I'm glad to help you with that. Can you please provide your planned travel dates?

USER: I would like to travel on May 13 and return on May 15.

ASSISTANT: Ok, may I know your class preference?

USER: I am comfortable with any of the class.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry to inform you that there are no flights available for you on those dates.

USER: It's ok, thank you for the information.

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