To write a function that performs a subtask and returns an answer.

When creating function definitions, it is important for a function to receive its input data via its parameters.

It is almost always a bad idea for a function that performs calculations to also perform any kind of console

input or output.

Trip Cost Function

For this question, write a function to help a travel agent calculate the cost of a trip for a family. The trip

includes a flight and some number of nights in a hotel. The hotel sleeps at most $2$ people in each room.

Write a Python function that takes four parameters as input and RETURNS the total cost of the trip. The

four parameters should be the airfare per person in dollars, the room cost per night in dollars, the number

of travellers, and the number of nights.

Importantly, your function should do no console input and no console output. It must receive its input

through its parameters and send its output using a return value.

Console I$/$O

In the main part of your program $($i$.$e$.$ NOT inside the function$$s body$),$ use console input to get the necessary

values needed by your function. You may assume that the user supplies valid input. Then call your function

using those values to get the total cost of the trip. Finally, display a message that indicates the total cost.