You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I have planned to visit Old state building at Boston on 09/20. Can you help me to book a direct flight?

ASSISTANT: Sure, may I know your name?

USER: I am Kathleen Harris.

ASSISTANT: Harris, can I know your return date?

USER: I will arrive on 09/22.

ASSISTANT: May I know your airport codes please?

USER: My landing is at Boston, MA - BOS. I want to fly from Washington DC - DCA.

ASSISTANT: Sorry, there is no flight available as per your requested dates.

USER: Ok, no issues. Thanks for your help and support.

ASSISTANT: You are welcome.