You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Emma Walker.

ASSISTANT: How may I assist you at this moment?

USER: Can you please help me to book a flight ticket from IAD to SEA?

ASSISTANT: Sure, I am glad to help you with that. Can you please provide your preferable departure and return dates of travelling?

USER: My departure date is on Sept 10 and return on Sept 12.

ASSISTANT: Is there any additional requirements do you have?

USER: I need a halt and price is 200.

ASSISTANT: Please wait a moment to check the flights on your route.

USER: Sure.

ASSISTANT: We regret to inform you that there are no flights moving on your route with your planned dates of travelling.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching us, have a great day.