You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am Shirley Allen. I am planning to do my birthday shopping at Washington,DCA. Can you please book a ticket on 07/12?

ASSISTANT: Sure, please provide me your source code?

USER: Source code is Detroit, DTW.

ASSISTANT: Kindly assign me your return date?

USER: Return will be on 07/14.

ASSISTANT: Please wait a minute..

USER: Sure.

ASSISTANT: Sorry, there were no flights with your given details.

USER: No problem. Thank you.

ASSISTANT: Thank you for reaching us.