You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I guide you for today?

USER: I would like to meet my sister on her birthday, could you please help me to book my flight ticket from SFO to PHX?

ASSISTANT: Can you please share on what dates you are willing to travel?

USER: Sure, I would like to depart on July 31st and return back on Aug 2nd.

ASSISTANT: Are you looking for a connecting flight or direct flight?

USER: I am looking for a connecting flight.

ASSISTANT: Do you have any class preferences?

USER: I prefer for an economy class.

ASSISTANT: Do you have any other requirements that you are looking for?

USER: Yes, I want to return back in the evening time.

ASSISTANT: Can you please provide your name to proceed further?

USER: My name is Donald Green.

ASSISTANT: Sorry, there are no flights available at your request.

USER: Sad to hear that, thank you for checking.

ASSISTANT: Thank you for contacting us, have a nice day.