pizza_count = 0

def make_pizza(size, top1="cheese", top2="cheese", top3="cheese"):
    '''include docstring
       understand function, positional - order matter in function call,
       named - order no longer matter,
       optional - may call a function with fewer number arguments
    '''
    global pizza_count  # understand the concept of local and global variables
    pizza_count += 1    # understand expression

    print('You order ' + str(size) + ' pizza with ' +
          top1 + ', ' + top2 + ', and ' + top3)

    # print('You order', str(size), 'pizza with', top1, top2, 'and', top3)
    # understand how to format output and work with multiple quotations

def get_total_pizza_order():
    return "total order: " + str(pizza_count) + " pizza"  # understanding of data type


make_pizza(12, "pepperoni", "mushroom", "pineapple")
make_pizza(16, "pepperoni", "mushroom")
make_pizza(20, "pepperoni")
make_pizza(20, top2="pepperoni")
make_pizza(size=12, top1="pepperoni", top2="mushroom", top3="pineapple")
make_pizza(size=16, top3="pepperoni", top1="mushroom", top2="pineapple")
make_pizza(20, top3="pepperoni", top1="mushroom")
make_pizza(16)

print(get_total_pizza_order())