01 / SOURCE

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Python source

import json
from math import ceil as round_up

# Data for our store: text, numbers, collections, and optional values.
prices = {"Milk": 2.99, "Bread": 1.50, "Eggs": 3.25}
categories = {"Dairy", "Bakery"}
store_location = (2, 4)
discount = None
store_open = True

# This for loop runs directly in the program, without a def.
for product in prices:
    print(product, prices[product])

requests = ["Milk", "", "Bread", "Soap", "CHECKOUT", "Eggs"]
cart = []
position = 0

while store_open and position < len(requests):
    product = requests[position]
    position += 1
    if not product:
        continue
    if product == "CHECKOUT" or product == "QUIT":
        break
    if product not in prices:
        continue
    cart.append(product)

def calculate_total(items, price_list):
    total = 0.0
    # This for loop is inside a function; both kinds remain in the program.
    for product in items:
        if product in price_list:
            total = total + price_list[product]
    return total

def ask_customer(default_name="Guest"):
    name = input("Your name: ")
    if not name:
        return default_name
    return name

class Receipt:
    def __init__(self, items, total):
        self.items = items
        self.total = total

def show(self):
        print("Items:", self.items)
        print("Total:", self.total)

def save(self, filename="receipt.json"):
        if not self.items:
            raise ValueError("Cannot save an empty receipt")
        payload = {"items": self.items, "total": self.total}
        with open(filename, "w", encoding="utf-8") as file:
            json.dump(payload, file)
        with open(filename, "r", encoding="utf-8") as file:
            saved_text = file.read()
        return saved_text

subtotal = calculate_total(cart, prices)
if discount is not None:
    subtotal = subtotal - discount
elif subtotal > 0:
    print("No discount applied")
else:
    print("Your cart is empty")

rounded_total = round_up(subtotal)
receipt = Receipt(cart, subtotal)
receipt.show()
print("Rounded up:", rounded_total)
print("Store location:", store_location)
print("Categories:", categories)

# Analyzing this example does not execute it or create a file.
try:
    saved = receipt.save(filename="receipt.json")
except (OSError, ValueError) as error:
    print("Receipt could not be saved:", error)
else:
    print("Saved receipt:", saved)
finally:
    print("Checkout finished")

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