# Help for this lesson for checking stock

#1

Logically this makes sense in my head... I mean if the stock is greater than 0 then run this line of code... yes. stock[calling item] item looks in the food list am I correct? total += prices[item] for the prices in the food list. correct in the previous lesson. Then I added the line stock[item] - 1. This makes sense in my mind, then I begin to wonder... Am I not getting this whole dictionary + functions things? Can anyone explain if I'm getting it wrong. And return total to close to close the function

``````shopping_list = ["banana", "orange", "apple"]

stock = {
"banana": 6,
"apple": 0,
"orange": 32,
"pear": 15
}

prices = {
"banana": 4,
"apple": 2,
"orange": 1.5,
"pear": 3
}

def compute_bill(food):
total = 0
for item in food:
if(stock[item] > 0):
total += prices[item]
stock[item] - 1

#2

this:

``stock[item] - 1``

won't reduce the stock, look:

``````i = 10
print i # 10
print i -5 # 5
print i # 10
i = i - 5
print i # 5``````

hope that helps

there is a reason you use `+=` increasing total, and not just `+`

#3

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