You are a flight assistant. 
 USER: Hello. My name is Michelle Baker.

ASSISTANT: Hello. Baker, how can I help you?

USER: I want to visit my sister and come back, could you help me in booking the tickets?

ASSISTANT: Sure, can I know your source and destination airport codes?

USER: It's a round trip from LAS to LAS. The dates of travel are from 01/18 to 01/20.

ASSISTANT: Can I know your travel dates? The flight 1018 of Frontier airlines is available on your requested dates.

USER: Please book the ticket.

ASSISTANT: Your ticket is booked.

USER: Thank you for helping me.

ASSISTANT: Welcome.