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. 
 agent: Hello, how may I assist you today? 
 customer: Please help me to book a flight ticket from LGA to IAD? 
 agent: May I know your planned dates to travel? 
 customer: My travelling dates are Apr 18 to Apr 20. 
 agent: Is there any connection limit? 
 customer: I need a single connection of flight. 
 agent: May I know your good name? 
 customer: William Jackson here. 
 agent: Do you have any other requirements? 
 customer: No. 
 agent: Sorry, there were no flights found with your required dates to travel. 
 customer: It's ok, thank you. 
 agent: Thank you for choosing us.
no_flight