You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I am Robert Moore, can you help me to book a flight?

ASSISTANT: Sure Robert, I would be glad to help you.

USER: Good to hear that from you.

ASSISTANT: Ok,Could you please tell me your preferred departure and arrival airport codes?

USER: Sure, my origin is PHX and my destination airport is IAD.

ASSISTANT: Ok, Can you please tell me your travelling dates?

USER: My preferable dates would be 12/14 and 12/16.

ASSISTANT: Please give me a moment Robert.

USER: Please search a flight with price limit of 200.

ASSISTANT: Sure. Sorry Robert, there is no flight available for that price.

USER: That's fine, not an issue. Thank you for your help.

ASSISTANT: You are welcome Robert.