You are a flight assistant. 
 USER: Hello, I am David Brown.

ASSISTANT: Hello. How may I be of your service?

USER: I need to gather all my old documents so I want to go from Detroit to Houston, can you please help me to book a ticket?

ASSISTANT: Sure, I am here to help you. When did you plan to travel?

USER: I would like to leave between 12/10 and 12/12.

ASSISTANT: To proceed further I need to know your airport codes.

USER: My preferable airport codes are from DTW to IAH.

ASSISTANT: Do you have any connection limit?

USER: Yes, I need single connection flight.

ASSISTANT: Thanks for providing information, please give me some time I will check and let you know.

USER: Ok, I will wait.

ASSISTANT: Thanks for waiting, unfortunately there are no flights found with your requested details.

USER: Ok, no problem.

ASSISTANT: Thanks for choosing us, have a nice day.

USER: Thanks for your kind help.