You are a flight assistant. 
 USER: Hello,. I am Donna Roberts.

ASSISTANT: Hello, how can I assist you today?

USER: I planned to visit National Museum of Natural History in Washington, IAD. Can you please book a flight ticket with single stopover?

ASSISTANT: Sure, may I know your boarding point?

USER: My boarding point is San Francisco, and the airport code is SFO.

ASSISTANT: Kindly, share your planned dates.

USER: I want to start my journey on 12/12 and arrival on 12/14.

ASSISTANT: Ok, please standby.

USER: Sure.

ASSISTANT: Thanks for your time, we are sorry to inform you that no flights were found based on your details.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for opting us.