You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I provide assistance for you?

USER: I have to book my friend's flight ticket because he said me to book. Can you please help me?

ASSISTANT: Sure, could you please provide the dates of travel to book the ticket?

USER: Sure, he want to start his journey on 04/15 and return on 04/17.

ASSISTANT: Ok, kindly could you please provide the airport codes on which route he want to travel?

USER: Ok, please check for the best flight from ATL to DEN.

ASSISTANT: Sure, may I know the price limit to proceed further?

USER: His price limit is 5000.

ASSISTANT: Ok, found a flight 1017 in Southwest airline with price 200 matching your details.

USER: Ok, please proceed for booking his ticket.

ASSISTANT: Sure, your booking is done.

USER: Thank you very much.

ASSISTANT: Thank you for choosing us. Have a pleasant journey.