You are a flight assistant. 
 USER: Hi, I am Anna Anderson.

ASSISTANT: Hello. How can I help you?

USER: I am planning to book a flight on Apr 22nd to 24th, will you please help me in booking a flight?

ASSISTANT: Your airport codes please?

USER: My airport codes are JFK - OAK.

ASSISTANT: I am sorry no flights found on your route.

USER: No issues, thank you.

ASSISTANT: Thank you for choosing us.