You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: My name is Ryan Thomas, please book me a plane ticket from PHL to SFO.

ASSISTANT: Sure, please share your planned dates of your journey.

USER: Sure, my trip dates are from 10/10 to 10/12.

ASSISTANT: Please hold on a moment.

USER: Ok.

ASSISTANT: Ryan, no flights has been found on your requested dates.

USER: It's ok, thank you.

ASSISTANT: Thank you for approaching us.