You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am Nicholas Lopez, want to alter my reservation dates. Can you please help me?

ASSISTANT: Sure, let me check your reservation status in our database.

USER: Sure.

ASSISTANT: Sorry, we couldn't found any reservation in our database.

USER: It's ok, thank you.

ASSISTANT: Thank you for choosing us.