You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I want to book a ticket from PHX to DCA. Could you book a ticket?

ASSISTANT: Sure, may I know the travelling dates?

USER: Depart is by Apr, 19 and return date is Apr, 21.

ASSISTANT: Do you have any connection limit?

USER: I would prefer connecting flight.

ASSISTANT: Is there any other requirements?

USER: No.

ASSISTANT: May I know your name?

USER: My name is Lisa Nelson.

ASSISTANT: Sorry, no flights found with your chosen dates.

USER: Thanks.

ASSISTANT: Thank you for opting us.