You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I'm Stephen Gonzalez. I am planning to attend music concert at Dallas, can you please help me with booking a flight ticket?

ASSISTANT: Sure, please tell me your travelling dates.

USER: Sure, I would like to take off on 05/25 and return back on 05/27.

ASSISTANT: Ok, please tell me your airport codes.

USER: My source airport code is PHL and the destination airport code is DFW.

ASSISTANT: Sorry, there is no plane on your requested travel dates.

USER: Ok, no issues. I will try another way to complete my trip. Anyways, thank you for checking.

ASSISTANT: Thank you.

USER: You are welcome.