You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I am planning to make a trip from IAD to LAX. Can you please help me with the booking?

ASSISTANT: Sure, I am happy to help you with that. Can I have your travel dates please?

USER: Sure, I want to depart on Apr 19 and need to return on Apr 21.

ASSISTANT: Ok, please let me know the timings of your journey.

USER: I am comfortable with any timings.

ASSISTANT: Ok, do you have any specific airlines preference?

USER: Yes, I prefer a normal-cost airline to travel.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: There is a airline which can provide a flight with business class. Are you fine with this?

USER: Ok, please proceed for booking.

ASSISTANT: May I know your good name please to book a ticket?

USER: Sure, my name is Dennis Mitchell.

ASSISTANT: Ok, your ticket booking has done and the flight number is 1029.

USER: Thank you.

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