In Python, `None` is a special object that represents the absence of a value. **If we don't specify any return value, `None` is used by default**.   
It is commonly used to indicate that a function does not return any meaningful result. Let's consider different cases when `None` return value can be used:

## First case
When the function does not have a specific result or value to return:

def greet(name):
    print(f'Hello, {name}!')

result = greet('Alice')
print(result)

In this case, the function `greet()` simply prints a greeting message but does not return any specific value. The default return value is `None`.

## Second case
When a function is used for its side effects or actions rather than a return value:

def save_data(data):
    # Save the data to a file or database
    # ...
	print('Data was saved succesfully!')

data = []
result = save_data(data)
print(result)  # Output: None

In this example, the function `save_data()` performs some actions to save data but does not return any specific result. The return value is `None`, but the focus is on the side effect of saving the data.

By the end of this course, you'll have a solid grasp of how important functions are in Python, no matter your field in computer science. We'll cover creating functions, defining arguments, handling return values, and exploring their use in Python.

Now we will consider what a function in Python and some basic techniques used to create functions is: what are the arguments of the function, what is the return value of the function, what is the body of the function, and how to use the function in the code.

Python is a fairly flexible language in terms of creating functions. This is especially true in setting function arguments - there are several different types of function arguments, and you can choose any of them depending on the problem you are solving. Let's now take a closer look at them.

This section of the Python course covers *args and **kwargs, which allow you to handle variable numbers of positional and keyword arguments in functions. `*args` lets you pass any number of positional arguments, making functions more flexible. **kwargs allows you to pass any number of keyword arguments as a dictionary, which facilitates handling complex data structures efficiently.

The return value of a function is the direct result of the execution of the function, which we can use in the program. There are several types of function return values - now we will consider the most commonly used.

Now it's time to consider additional topics to help make your functions more flexible and solve more complicated tasks. You will understand recursion, lambda functions, and some basics principles of writing effective and maintainable functions.

Python Functions Tutorial

None Return Value

First case

Second case

Python Functions Tutorial

None Return Value

First case

Second case