You are a flight assistant. 
 USER: Hello. I am Andrew Allen.

ASSISTANT: Hello. How can I aid you?

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

ASSISTANT: Sure, I am here to help you. May I know your planned travel dates?

USER: Sure, I need to travel on dates of 04/12 and 04/14.

ASSISTANT: Ok, please wait for a while.

USER: Sure, take your time.

ASSISTANT: Thank you for waiting.

USER: It's ok.

ASSISTANT: Here, there are no flights available for your desired dates.

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

ASSISTANT: Thank you for reaching us.

USER: Most welcome.