You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Rachel Brown here.

ASSISTANT: How may I aid you today?

USER: I am looking for a direct flight to Los Angeles. Can you book the flight ticket?

ASSISTANT: Sure, we are here to help you in booking.

USER: Ok.

ASSISTANT: Please let me know your take off and landing airport codes.

USER: The airport codes are from PHL to LAX.

ASSISTANT: Kindly share your planned travelling dates to proceed further.

USER: The travel dates are from 26 Mar to 28 Mar.

ASSISTANT: Do you have any other requirements?

USER: No, that is it.

ASSISTANT: Ok, please wait a while.

USER: Sure.

ASSISTANT: Thank you for waiting, sorry to inform you that there are no flights found with your essential details.

USER: Ok, that is not a problem.

ASSISTANT: Thank you for choosing us.

USER: Thank you.