You are a flight assistant. 
 USER: Hello, I am Daniel Baker.

ASSISTANT: Hello, how may I help you?

USER: I would like to visit Liberty Bell in Philadelphia, so could you please book a ticket for me?

ASSISTANT: Definitely. Please share your travel dates.

USER: I would like to go on 04/09 and return back on 04/11.

ASSISTANT: Can I have your nearby airport codes?

USER: My source and destination airport codes are HOU and PHL.

ASSISTANT: Please wait for a moment. Sorry, there is no flight available on your route.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome. Thank you for reaching us.

USER: Welcome.