Could you please explain me this concept step by step?

Question

def fun(a):
x=a**2
y=0
while x>1:
x=x-1
y+=2
return y
print (fun (1)+fun(2))

Answer 1

For func(1)
x=1**2
x=1
y=0
While x>1 is false
So return Y
func(1) returns 0

For func(2)
x=2**2
x=4
y=0
While x>1:
x=4-1=3
y=y+2=2

while 3>1:
x=3-1=2
y=y+2=2+2=4

while 2>1:
x=2-1=1
y=4+2=6

Now while x>1 is false
so y is returned

fun(2) returns 6

print(fun(1)+fun(2))
Prints 0+6=6