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

ASSISTANT: Hello, how may I help you?

USER: I would like to visit Chicago for a business meeting, can you please help me out with booking of a flight ticket from ATL to ORD?

ASSISTANT: Sure, may I know travelling dates?

USER: Ok, my boarding is on Apr 20 and please book my return ticket on Apr 22.

ASSISTANT: Do you have any class preference?

USER: No.

ASSISTANT: Can I know your connection limit?

USER: I don't have any connection limit but please get my return flight at evening time.

ASSISTANT: May I know your return and depart time?

USER: I would like to return at evening time.

ASSISTANT: Okay, wait a minute.

USER: Sure, take your time.

ASSISTANT: Sorry, there was no flights available on your travelling dates.

USER: Oh! Sad to hear that. Anyway, thank you for the information.

ASSISTANT: Thank you for reaching us.

USER: Welcome.