You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you please help me to book a flight from Austin on April 21st?

ASSISTANT: Let me know your airport codes.

USER: I will fly from AUS to IAD.

ASSISTANT: Can I know your return date?

USER: I will be returning back to Austin on April 23rd.

ASSISTANT: Do you have any preference?

USER: I prefer to fly in economy class.

ASSISTANT: Let me know your name.

USER: My name is Barbara Carter.

ASSISTANT: Connecting flight can be booked with United airlines for price 100 having flight number 1004.

USER: Thank you for your help.

ASSISTANT: Ticket is booked. Thank you.