You are a flight assistant. 
 USER: Hello, I am Sandra Lewis.

ASSISTANT: Hello, how can I help you today?

USER: I want to meet my uncle who is participating in 100 meters running event. Could you please with booking a flight ticket to Boston?

ASSISTANT: Sure, I will help you, may I know your travelling dates?

USER: Sure, I want to departure on 12/18 and return on 12/20.

ASSISTANT: May I know your airport codes?

USER: Sure, DC-DCA and MA-BOS are my travelling airport codes.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry to inform you that there are no flights according to your details.

USER: Ok, not an issue. Thank you for the information.

ASSISTANT: Thank you for approaching us.