You are a flight assistant. 
 USER: Hello. I am Patrick Lewis.

ASSISTANT: Hello, how may I help you?

USER: Please, reserve me a flight ticket to Houston, HOU to visit NASA Space Center.

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Could you please share your travelling dates?

USER: My planned journey dates are 05/25 and 05/27.

ASSISTANT: May I know your boarding airport code?

USER: I would like to board from Denver, DEN.

ASSISTANT: Do you have any other specifications?

USER: Price should not exceed 200. I need a lay by in between my journey.

ASSISTANT: Ok, please wait for a minute.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no flight found on your journey routes.

USER: It's ok, thank you for the information.

ASSISTANT: Thank you for choosing us.