Decorators is a concept that belongs to the Functional Programming and you can't find this concept in procedural programming like C/C++ or Object Oriented Programming like Java, Php. Decorators allow you to use another function inside a function and you can use that function to perform different tasks without changing the original function code. Simple understand this concept as "Using Function Inside a Function" Here's a simple program in python which demonstrates the concept of decorators.

```
def higher_function():
    def lower_function():
        print("How you doing")
    lower_function()
 
higher_function()
```

You can see the output as:

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![Screenshot_2.png](https://images.hive.blog/DQmTMZBvJcUigf9nCunhXgoMoEmbmDNiYqvVmeMqJh26ito/Screenshot_2.png)
</center>

Now let's see the working of decorators. We would create a function that subtracts two values like if we passed (3,5) then it will return -2 as output but remember we want to subtract 3 from 5 and returns output as 2 (not negative). Then in this case we use decorators to modify existing function class that subtracts two values.

```
def subtraction(x,y):
    print(x-y)
    
def sub(func):
    def operation(x,y):
        if x<y:
            x,y=y,x
        return func(x,y)
    return operation

subtraction=sub(subtraction)

subtraction(5,10)
```

You can see the output as follows:
<center>
![Screenshot_3.png](https://images.hive.blog/DQmP7QUpfwS8V4CxbfDjnKcuu5iZQYUNWqZ5Rg6CpJokZSi/Screenshot_3.png)
</center>