You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am Nicholas Young. Please book me a flight ticket to Washington DCA to meet my sister, can you help me with booking?

ASSISTANT: Sure, kindly provide me your travel dates?

USER: I will fly on 04/17 and return on 04/19.

ASSISTANT: Can you please mention me your take off airport code?

USER: My takeoff airport code is Detroit DTW.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry to say, no flight found with your requirement.

USER: Ok, no issues. Thank you.

ASSISTANT: Thanks for reaching us.