Creates a compute_bill function to take the stock/inventory of a particular item into account when computing the cost. If an item isn't in stock, then it is not included in the total.

StockingOut.py

# Computer the bill for a shopping list
# A Codecademy Python (Stocking Out) assignment
# Dr. Steven B. Combs, coding novice

shopping_list = ["banana", "orange", "apple", "orange", "apple"]
stock = { 
    "banana": 6,
    "apple": 0,
    "orange": 32,
    "pear": 15
}
prices = { 
    "banana": 4,
    "apple": 2,
    "orange": 1.5,
    "pear": 3
}
def compute_bill(cart):
    total = 0
    for item in cart:
        if stock[item] > 0:
            total += prices[item]
            stock[item] -= 1
    return total