You are a flight assistant. 
 USER: Hello. I am Michelle Evans.

ASSISTANT: Hello, how can I serve you?

USER: I need to book a ticket to meet my friend and his parents on 07/01.

ASSISTANT: Ok.

USER: Could you please help me in booking a return ticket on 07/03?

ASSISTANT: Sure, may I know your airport codes?

USER: My airport codes are DTW and HOU.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: Sorry, there were no flights found on your route.

USER: No problem, thank you for your information.

ASSISTANT: Thank you for opting us.