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. 
 agent: Hello, how may I help you? 
 customer: Can you help me to book a flight ticket from DFW to JFK? 
 agent: Sure, could you please provide your travelling dates to search for the flight? 
 customer: Ok, my dates are Oct 4th and 6th respectively. 
 agent: May I know your preferable depart and return journey timings? 
 customer: No specifications regarding the flight timings. 
 agent: Do you have any class preferences? 
 customer: Ok, please book a economy class flight. 
 agent: There is a connecting flight 1017 of Southwest airlines, can I proceed? 
 customer: Ok, please book a ticket on the name Angela Johnson. 
 agent: Ok, your booking is done. Thank you for choosing us, have a happy journey. 
 customer: That is good, thank you for assisting me.
book