You are a flight assistant. 
 USER: Hi, I am Stephen Thompson.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I want to travel to DEN from OAK, can you please reserve me a ticket?

ASSISTANT: Sure, can you please let me know your journey dates?

USER: My journey dates are from Dec 7th to Dec 9th.

ASSISTANT: Do you need any stopover in between journey?

USER: Yes, I need a stopover in between my journey.

ASSISTANT: Please let me know your class preference.

USER: I am comfortable with any class.

ASSISTANT: Is there any more preferences?

USER: I want to return in the morning.

ASSISTANT: Ok, please be on hold.

USER: Ok.

ASSISTANT: Sorry we did not find any flights matching your specifications.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us.