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: Hi. 
 agent: Hello, how may I assist you? 
 customer: I am Joshua Mitchell. I just want to change my reservation to next week, because I have some work in this week. Can you help me in changing my reservation? 
 agent: Sure, I will help you.Please give me a momentr. 
 customer: Sure. 
 agent: Sorry, no reservation showing on your name. 
 customer: Ok, not an issue. 
 agent: Thank you for reaching us. 
 customer: Thank you for your help. 
 agent: You are welcome.
Student:
no_reservation