How these recursion works?

Question

hey, can anyone explain to me how these recursion works?

def Sum(n):
if n == 0
s=0
print (s)
else:
s=n+Sum(n-1)
return s
print Sum(10)

many thanks :)

Answer 1

Recursion is when one function call itself. In this example first n = 10 then
s = 10 + 9 + 8 ... while n = 0 and then it print(0).

Answer 2

but s=n+Sum(n-1)
means:
I. 10+10-1= 19
II. 9+ 9 -1= 17
III. 8+ 8 -1=15
.
.
.
..
right?

Answer 3

No, s=n+Sum(n-1)
means:
I. 10+sum(10-1)(function Sum(9)(with 9 as argument) will again run)
II. 10+ 9 +sum(9-1)=
III. 10+9+8+sum(8-1)
.
.
.
..

Answer 4

aah i understand. thanks a lot