I'm trying to practice the example but it isn't working?

I attempted to do the exercise that was given in the example, the about about getting food out of the refrigerator and cooking it, but my code does not work:

class Refrigerator:
    cooling = True
class Microwave:
    working = True
    def cook(self, food):
        return ["cooked "+item for item in food]

def get_food_from_fridge(food = []):
    if Refrigerator.cooling == False: raise RefrigeratorException
    else: return food

def heat_food(food):
    if Microwave.working == False: raise MicrowaveException
    else: return Microwave.cook(food)

    food = get_food_from_fridge(["carrots", "potato"])
    food = heat_food(food)
except KitchenException:
    food = order_takeout()

The above code raises the following TypeError:
TypeError: cook() missing 1 required positional argument: 'food'

I do not understand why? Could someone explain?

Try including print statements to keep track of the steps of what is ending up being given as an argument to cook().