You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I aid you today?

USER: I am Joshua Mitchell want to visit IAD, can you book a ticket from IAH?

ASSISTANT: Sure, I am happy to help you. May I know your travelling dates?

USER: Sure, my travelling dates will be 06/13 and 06/15.

ASSISTANT: Sorry to say that, there are no flight's available based on your travelling dates.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for contacting us. Have a great journey.