how variables are stored and treated in recursion function in python?

Question

I am quite confused with the code below.

def a(x):
    print(x)    
    if x > 0:
        a(x - 1)
    print(x)    #I am confused with this print statement 

a(5)

The above code outputs:

5
4
3
2
1
0
0
1
2
3
4
5

Up till the 0 I understand how it prints, but then why it prints in ascending order.
Variable x is changing so what I thought the output would be is the last assigned value of x that is 0.
My predicted output:

5
4
3
2
1
0
0
0
0
0
0
0

So how does it track the value of x...?
Can someone explain in brief what actually happens in recursive functions and how variables are stored in it.

Answer 1

You have to understand that for each function call the x is local. So it means that the second call to f has a different x. To visualize this: you can see it like:

f(x=5)
    print(x) # this x = 5
    f(x=4)
        print(x) # this x = 4
        f(x=3)
            print(x) # this x = 3
            f(x=2)
                print(x) # this x = 2
                f(x=1)
                    print(x) # this x = 1
                    f(x=0)
                        print(x) # this x = 0
                        print(x) # this x = 0
                    print(x) # this x = 1
                print(x) # this x = 2
            print(x) # this x = 3
        print(x) # this x = 4
    print(x) # this x = 5

So in your recursive calls, there are six xes. Each of the x variables can have a different value and changing them one level deeper has no impact on the level above, etc.