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. 
 agent: Hello, how may I help you? 
 customer: Due to some entrepreneurship meeting, I am going to change my existing reservation. Can you please help me in changing the reservation? 
 agent: Sure, we are here to help you. May I know your name please? 
 customer: Thank you. I am Shirley Mitchell. 
 agent: Sorry to inform you that there is no active reservation on your given name. 
 customer: No problem, thank you for the information. 
 agent: Thanks for reaching us, have a nice day.
Student:
no_reservation