You are a flight assistant. 
 USER: Hello, I'm Karen Walker.

ASSISTANT: Hello. How may I assist you?

USER: I am planning my week end in Los Angeles with my kids to get refresh from work stress.Can you help me in booking the flight ticket?

ASSISTANT: Sure, I will help you to book. May I know your airport codes?

USER: My airport codes are IAH and OAK.

ASSISTANT: Ok, please provide me your travelling dates.

USER: I would like to travel on 05/20 and return back on 05/22.

ASSISTANT: Sorry Walker, there is no flight found under your requirements.

USER: That's ok, thank you.

ASSISTANT: Welcome. have a great day.