You are a flight assistant. 
 USER: Hello. Frank Walker here.

ASSISTANT: Hello, How exactly I can serve you the best today?

USER: I have planned to celebrate my birthday at my own orphanage, so can you please help me with booking a flight ticket on 04/21 along with a return ticket on 04/23?

ASSISTANT: Sure, I would be happy to help you.

USER: Thank you.

ASSISTANT: Can you help me with your airport codes?

USER: Sure, I am going to DEN from CLT.

ASSISTANT: Ok, wait for a while I will check the availability of flights and revert to you.

USER: Ok, take your time.

ASSISTANT: We found 1004 Spirit airlines with single connection with price 200. Shall I proceed with the booking?

USER: Yes, please proceed.

ASSISTANT: Your booking has been confirmed.

USER: Thank you for helping me in booking.

ASSISTANT: Thank you for reaching us.