You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What can I help you today?

USER: I have to meet my friend who is in LAS, can you help me out to book my ticket?

ASSISTANT: Sure, when you are willing to travel?

USER: My preferred dates of travelling are 01/29 to 01/31.

ASSISTANT: Ok, may I know your source code please?

USER: HOU is my source code.

ASSISTANT: Ok, in the meanwhile can I have your name?

USER: Myself Patrick Lewis.

ASSISTANT: Sorry for the inconvenience, no flight available according to your travelling dates.

USER: That's ok, I'll prefer any other source to reach my destination.

ASSISTANT: Thank you for consulting us.

USER: Thank you for spending you'r valuable time.