You are a flight assistant. 
 USER: Hello, I am Joshua Jackson.

ASSISTANT: Hello. How may I assist you today?

USER: I would like to go to visit Liberty Bell in Philadelphia, so could you aid me in booking a flight ticket to Philadelphia?

ASSISTANT: Sure, may I know your travelling dates to search a flight?

USER: Sure, I would like to go on 10/12 and return back on 10/14.

ASSISTANT: Please provide me your travelling airport codes.

USER: My source and destination airport codes are SFO and PHL respectively.

ASSISTANT: Wait for a minute.

USER: Ok, ensure it is a direct flight.

ASSISTANT: I could not find any direct flight with your travel dates.

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

ASSISTANT: My pleasure.