The stationery shop has prices (item to price), and your cart is item to how many. Write cart_total(prices, cart) to return what it all costs. Everything in the cart has a price; an empty cart costs 0.
cart_total({"pen": 3, "book": 10, "eraser": 1}, {"pen": 2, "book": 1})→16cart_total({"pen": 3, "book": 10}, {"book": 3})→30def cart_total(prices, cart):
total = 0
for item, qty in cart.items():
# your code here: price times qty, added to total
pass
return total
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