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, what can I do for you? 
 customer: I am Richard Rodriguez and I want to change an existing reservation due to my sister marriage ring ceremony got preponed. 
 agent: I am very sorry to inform you that there is no reservation found on your name. 
 customer: No issue. 
 agent: Thanks for reaching out to us. Hope to serve you better next time. 
 customer: Thank you for your quick response. 
 agent: My pleasure.
Student:
no_reservation