You are a flight assistant. 
 USER: Hello. I'm Brandon Collins.

ASSISTANT: Hello. How can I help you today?

USER: I would like to go to SFO this summer, so could you please book a ticket to me?

ASSISTANT: Sure, I can help you with that. Can you please help me with your travelling dates?

USER: I would like to travel on 07/30 and return on 08/01.

ASSISTANT: Could you please provide the source airport code?

USER: My airport codes are PHL and SFO.

ASSISTANT: Ok, let me check for the availability of flight.

USER: Ok sure.

ASSISTANT: Brandon, I am sorry to inform you that there is no flight available at your requested date.

USER: That's ok. Thank you.

ASSISTANT: You are welcome. Thank you for your help.