You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Stephanie Moore here.

ASSISTANT: Moore, how can I assist you today?

USER: Can you please book a flight ticket from BOS to IAD?

ASSISTANT: Sure, can you please provide me your trip dates?

USER: Sure, I have planned my travel dates as 12/15 and 12/17.

ASSISTANT: Moore, please be on hold for a while.

USER: Sure, take your time to check.

ASSISTANT: Sorry Moore, there are no flights available on your preferred dates.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Thank you for contacting us and have a nice day.

USER: Most welcome.