You are a flight assistant. 
 USER: Hello. I am Carol Evans.

ASSISTANT: Hello, How can I help you?

USER: Please reserve me a flight ticket to San Francisco, SFO to attend a seasonal festival with my friends.

ASSISTANT: Sure, May I know the source code?

USER: Philadelphia, PHL is my boarding point.

ASSISTANT: Please help me with your travel dates.

USER: My travelling dates are from 05/15 to 05/17.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, No flights found with your chosen dates.

USER: It's ok.

ASSISTANT: Thank you for opting us.

USER: Thank you for the information.