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. 
 customer: Margaret Lopez here. 
 agent: Can you please tell me how can I assist you? 
 customer: I am planning to book a ticket from PHX to SEA to meet my parents. 
 agent: May I know your travelling dates? 
 customer: My preferable journey dates are from 08/18 to 08/20. 
 agent: As per your details there is no flight for you to book ticket. 
 customer: Ok, no issues. 
 agent: Thank you for contacting us. 
 customer: Thank you for your information.
Student:
no_flight