Teacher: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
Teacher: Now, understand the problem? Solve this instance: customer: Hello, I am Anthony Smith. 
 agent: Hello, what can I do for you? 
 customer: Can you help me to change an existing reservation due to my health issues? 
 agent: Sure, give me sometime to check and get back to you. 
 customer: Sure. 
 agent: Unfortunately we didn't found any reservation according to your name. 
 customer: Ok, not an issue. Thank you for your information. 
 agent: Thank you for choosing us.
Student:
no_reservation