You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I'm planning to visit Oakland hills, can you book a ticket from DCA to OAK?

ASSISTANT: Sure, we are here to help you. Can you share me your travelling dates?

USER: I would like to depart to depart from my source location on 12th Sept and I want to return back by 14th Sept.

ASSISTANT: May I know your name?

USER: My name is Helen Evans.

ASSISTANT: Do you have any other specifications?

USER: I don't have any other specifications.

ASSISTANT: Ok, wait for some time.

USER: Sure, I'll wait for your response.

ASSISTANT: Thanks for waiting there are no flights found on your details.

USER: Oh! That's ok, thank you for giving the information anyways.

ASSISTANT: Thanks for approaching us.