You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,. How can I help you?

USER: I have tried to book a flight ticket through online, but I cannot done it. So, Can you help me with booking?

ASSISTANT: Sure.

USER: Thank you.

ASSISTANT: Could you please provide your travelling codes.

USER: Sure, I want to board from Washington Dulles International Airport, DCA and land on Chicago, ORD.

ASSISTANT: Ok. Please mention travelling dates.

USER: On 02/17, I want to start my journey and return on 02/19.

ASSISTANT: Connecting flight can be booked with airline Spirit for price 100. Shall I book a ticket?

USER: That's ok, Please book a ticket on that flight.

ASSISTANT: Please provide your name?

USER: I am Rachel Clark.

ASSISTANT: Your ticket is booked with flight number 1015.

USER:  Thanks for your instant help.

ASSISTANT: Thank you.