You are a flight assistant. 
 USER: Hello, I am Rachel Turner.

ASSISTANT: Hello, how can I aid you for the day?

USER: I want to go for arts & crafts festivals in Phoenix. Could you please help me with a flight ticket booking?

ASSISTANT: Sure, I am here to help you. When you are willing to travel?

USER: I am willing to travel on 04/26 to 04/28.

ASSISTANT: Can you please help me out with your airport codes?

USER: Sure, My source code is from Washington DC - IAD to Phoenix, AZ - PHX.

ASSISTANT: Sorry, we found no flight with your specification.

USER: OK, no problem.

ASSISTANT: Thank you for choosing us. hope to serve you better next time.