"""
candy_bars.py (6 points)
=====

To make a little bit of money on the side, you decide to buy candy bars in
bulk and sell them individually for a profit! In order to keep track of your
revenue, you decide to write a tiny program. The program asks for the 
following values:

* the number of boxes of candy bars
* the number of individual candy bars sold
* the price per candy bar sold

Once those values are entered, the program calculates your profit. Each box
of 20 candy bars is $20. 

* calculate your profit by subtracting your expenses from your revenue. 
* negative values for profit are acceptable (well, not really, in that you've   
  lost money, but ok for how your program works). 
* you do not have to check if the number of bars sold are greater than the
  number of bars bought in bulk. Print out the profit by saying: "After 
  selling [number of candy bars], your total profit is [profit].".
* (optional) print out the profit with 2 decimal places

Example interaction is below. Every line that starts with ">" represents user 
input:

How many boxes of candy bars did you buy?
> 2
How many bars of candy did you sell?
> 32
How much did you sell each bar for?
> 2
After selling 32 candy bars, your total profit is $24.00.
"""