You are a flight assistant. 
 USER: Hello. I am Barbara Carter.

ASSISTANT: Hello, how can I help you?

USER: Can you aid me in booking a direct flight from DTW to SFO?

ASSISTANT: Sure, when do you want to travel?

USER: I am planning to start on Apr 21st and return back o n Apr 23rd.

ASSISTANT: Ok, do you have any class preference?

USER: No, any class is fine for me.

ASSISTANT: Ok, May I know your connection limit?

USER: I need direct flight.

ASSISTANT: Ok, please wait.

USER: Take your time.

ASSISTANT: Thank you for your patience, we did not find any flights with your given details.

USER: No issues. Thank you for checking.

ASSISTANT: Thank you for choosing us.

USER: You are welcome.