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

ASSISTANT: Hello. How can I aid you?

USER: I want to book a direct flight to washington , please help me .

ASSISTANT: Sure, Can I know your travelling dates?

USER: My travelling dates are from 12/24 to 12/26.

ASSISTANT: Please share me your airport codes.

USER: I want to fly from SEA to IAD.

ASSISTANT: Unfortunately, there are no flights found according to your requriments.

USER: No issues, thank you.

ASSISTANT: Thank you for picking us.