Given the task definition and input, reply with output. 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. I am Angela Taylor. 
 agent: Hello. How can I help you? 
 customer: Owing to an emergency, I would like to cancel my recent reservation. Can you please help me with that? 
 agent: Ok, please wait I will revert you. 
 customer: Sure. 
 agent:  Sorry, no reservation found on your name. 
 customer: Thank you for your assistance. 
 agent:  Thank you for approaching us.
no_reservation