How to use function defaults in Python

def greet(name="Guest", greeting="Hello", punctuation="!"):
    """Return a greeting message using default parameters."""
    return f"{greeting}, {name}{punctuation}"

def describe_pet(pet_name, animal_type="dog"):
    """Display information about a pet with a default animal type."""
    print(f"I have a {animal_type} named {pet_name}.")

def multiply(x, y=2, z=3):
    """Multiply numbers, using defaults for missing arguments."""
    return x * y * z

if __name__ == "__main__":
    # Using defaults for all parameters
    print(greet())

    # Overriding some defaults
    print(greet("Alice"))
    print(greet("Bob", "Hi"))
    print(greet("Charlie", "Hey", "."))

    # Demonstrating a function with a default parameter
    describe_pet("Rex")
    describe_pet("Whiskers", "cat")

    # Function with multiple defaults
    print(multiply(5))          # 5 * 2 * 3 = 30
    print(multiply(5, 4))       # 5 * 4 * 3 = 60
    print(multiply(5, 4, 2))    # 5 * 4 * 2 = 40