You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I am Donald Roberts. I would like to visit Chicago to meet my sister, can you please help me to book a flight ticket from IAH to ORD?

ASSISTANT: Sure, I will help you in booking your flight ticket. Please let me know your travel dates.

USER: Sure, my itinerary dates are Sept 11 and Sept 13.

ASSISTANT: Ok, do you have any other requirements?

USER: I would like to return in the afternoon time.

ASSISTANT: As per your requirements, there is no flight available.

USER: That's ok, thank you for your information.

ASSISTANT: You are welcome and thank you for contacting us.