In this task, you are given a conversation between a flight agent and the customer. You are given 4 options and you need to select the goal of the conversation. It is provided as part of customer's context, which has to be one of the following: `book`: Make a new reservation, `cancel`: Cancel an existing reservation, `no_flight`: No flight found for the customer's preference, `no_reservation`: No reservation / No change / No cancellation was made in the conversation, mostly enquiring details

customer: Hello. 
 agent: Hello. How can I help you? 
 customer: I am Karen Walker. I want to change my existing reservation, due to some health issue. Can you please help me? 
 agent: Sure, I will help you to change your reservation. 
 customer: Thank you. 
 agent: There is no reservation found on your name to change. 
 customer: It's ok, thank you for checking. 
 agent: Welcome.
no_reservation