You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Can you book a flight ticket from PHX to BOS?

ASSISTANT: Sure, may I know your trip dates?

USER: I want to take off on Dec, 11 and return back on Dec, 13.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: May I know your name?

USER: Richard Adams.

ASSISTANT: Sorry, there is no flight available.

USER: It's ok, no worries. Thank you.

ASSISTANT: Most welcome.