class BankAccount: def __init__(self, owner, balance): self.owner = owner self.__balance = balance # Private attribute def deposit(self, amount): if amount > 0: self.__balance += amount print(f"Deposited {amount}") def withdraw(self, amount): try: if amount > self.__balance: raise ValueError("Insufficient funds") self.__balance -= amount except ValueError as e: print(f"Error: {e}") # Usage acc = BankAccount("John", 1000) acc.deposit(500) acc.withdraw(2000) # Triggers error handling

<!-- HTML Form --> <form action="/login" method="POST"> <input type="text" name="username" /> <button>Login</button> </form> # Python Handler (Concept) def do_POST(self): content_length = int(self.headers['Content-Length']) post_data = self.rfile.read(content_length) # Process login logic...

# models.py class Product(models.Model): name = models.CharField(max_length=100) price = models.DecimalField(max_digits=10, decimal_places=2) category = models.ForeignKey(Category, on_delete=models.CASCADE) # views.py def product_list(request): products = Product.objects.filter(price__gt=100) return render(request, 'shop/list.html', { 'products': products })