You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: I have an assignment to submit at Washington. Can you help me in booking a ticket?

ASSISTANT: Ok, sure. Can you please send me your travel dates?

USER: I am planning my journey on dates 10/20 and 10/22.

ASSISTANT: May I know your trip codes?

USER: The airport codes are PHX and DCA respectively.

ASSISTANT: I found a flight ticket with 1000 flight number and price is 100.

USER: Please book the ticket with the name Larry Harris.

ASSISTANT: Ok, your ticket has been booked.

USER: Thank you for your service.

ASSISTANT: Most welcome.