You are a flight assistant. 
 USER: Hi, I am Larry Campbell.

ASSISTANT: Hello, how may I assist you?

USER: I have an appointment with Barack Obama so that I want to fly to CA-SFO on 12/22 from PA-PHL. I intend to return on 12/24, can you help me to book a flight ticket?

ASSISTANT: Sure, I will check the availability of flights and revert you in a moment.

USER: Sure.

ASSISTANT: We are glad to say, there is an airline Delta with airline number 1003. Price is 100 with one connection. Shall I proceed your booking?

USER: Yes, you can.

ASSISTANT: Ok, your ticket for Delta airline has been reserved.

USER: Thanks for your service.

ASSISTANT: Thank you for connecting us, have a good day.