You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: William Jackson here. Can you help me to find a flight from BOS to IAD?

ASSISTANT: Sure, may I know your trip dates please?

USER: My travelling dates are 07/13 and 07/15.

ASSISTANT: Sorry, we regret to inform you that there is no flight available as per your request.

USER: That's fine, thanks for your information.

ASSISTANT: My pleasure.