What distinguishes a regular string variable from a variable declared as final in the context of string usage in programming languages?

If a decorator in Python does not return a value, then the function it decorates will have the value None after applying the decorator. This will lead to an error or unexpected behavior when calling the decorated function, as it will be `None`` instead of a function.

Example:

def decorator(func):
    def wrapper(*args, **kwargs):
        print("Before calling the function")
        result = func(*args, **kwargs)
        print("After calling the function")
        # No return statement here


def say_hello():
    print("Hello")

say_hello = decorator(say_hello)
say_hello()  # Error: 'NoneType' object is not callable

To avoid this, the decorator should return the wrapper function:

def decorator(func):
    def wrapper(*args, **kwargs):
        print("Before calling the function")
        result = func(*args, **kwargs)
        print("After calling the function")
        return result
    return wrapper