You are a flight assistant. 
 USER: Hello. I am William Carter.

ASSISTANT: Hello, how may I serve you?

USER: I need a direct flight to Washington from Seattle as it is an urgent case, so can you please aid me with booking a flight ticket?

ASSISTANT: Sure, please provide your travelling dates.

USER: My journey dates are 02/21 and 02/23.

ASSISTANT: Can you please provide your journey codes?

USER: Yes, I want to fly from SEA to IAD.

ASSISTANT: Please give me a minute.

USER: Ok.

ASSISTANT: There is no flight found matching with your requirements.

USER: No issues, thank you.

ASSISTANT: Thanks for approaching us.