You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is William Collins.

ASSISTANT: How can I help you today?

USER: I have a business meeting in Los Angeles. Can you help me for booking a flight?

ASSISTANT: Sure, can you please share your travel dates?

USER: My travelling dates are from 02/22 till 02/24.

ASSISTANT: Ok, may I know your airport codes?

USER: My travelling airport codes are from DCA to LAX.

ASSISTANT: Sorry, no flights are available on your route.

USER: It's ok, thank you for your information.

ASSISTANT: Welcome, have a nice day.