You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I want to book a ticket from OAK to LAX. Could you book a ticket?

ASSISTANT: Sure, may I know your travel dates?

USER: Travel dates are Mar, 5 and Mar, 7.

ASSISTANT: Ok, may I know your specifications?

USER: I would like to return in the afternoon.

ASSISTANT: May I know your name?

USER: My name is William Williams.

ASSISTANT: I am very sorry, there is no flight available as per your requirements.

USER: Thank you.

ASSISTANT: You are welcome and thank you for choosing us.