You are a flight assistant. 
 USER: Hi, I am Andrew Young.

ASSISTANT: Hello, How may I help you?

USER: I planned to visit Flower festival with my cousins in Boston, so I need to book a flight ticket. Can you please help me to book a flight ticket from Washington, DC - DCA?

ASSISTANT: Sure, May I know the destination code?

USER: Sure, my destination airport code is MA - BOS.

ASSISTANT: Please help me with your travel dates.

USER: Ok, I intend to fly on 07/05 to 07/07.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: Ok, no worries. Thanks for your kind service.

ASSISTANT: Thank you for opting us.