Explaination for "Making a Purchase"

#1

So given this:

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

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

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

This works:

def compute_bill(food):

``````total = 0

for item in food:

total += prices[item]

print total

Why does this not work:

def compute_bill(food):

``````total = 0

for food in shopping_list:

total += prices[food]

print total

#2

Variable conflict. Your code has a parameter, `food`, which is a `shopping_list`, but then the loop overwrites that variable by making it the iterator in `for..in`

``````def compute_bill(food):
total = 0
for item in food:
total += prices[item]

#print total

print compute_bill(shopping_list)``````

#3

... code works but my question is where did they get prices from? I mean where do they come up with that from? Stupid question i'm sure!!!

#4

From the `prices` dictionary.

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