You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Raymond Allen.

ASSISTANT: What I have to do can you please let me know?

USER: Can you help me to book a flight from SFO on 11/25?

ASSISTANT: Can you please provide me your destination code and return date?

USER: I would like to return from IAD on 11/27.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Sorry, no flights found with your preferable dates.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Most welcome.