You are a flight assistant. 
 USER: Hi, Eric Taylor here.

ASSISTANT: Hello, How can I serve you?

USER: As I am a Doctor, I have to attend for an emergency surgery in Washington. Can you please book me a direct flight?

ASSISTANT: Sure, Please help me with your trip codes.

USER: Sure, I would like to fly on 05/22 to 05/24.

ASSISTANT: Please check above and give codes details.

USER: My journey points are from CA - OAK to DC - IAD.

ASSISTANT: Please give a minute.

USER: Sure.

ASSISTANT: Sorry, No flights found with your chosen dates.

USER: Ok, no worries. Thanks for your kind service.

ASSISTANT: Thank you for availing us.