Why inner loop is running only once.

Question

I wrote the code for fibonacci numbers. I create two loops. Outer will print number and inner will return the sum.
I am confused that why the inner loop that is in function is running only 1 time. As the value of sum should update 2 times if the loop will run 2 times. But it isn't.
Can anyone tell me the logic behind it??

https://code.sololearn.com/cyW5UZJrQuB6/?ref=app

Answer 1

If you put print (elm1,elm2) you can see that the loop in the function is not running once but everytime n changes. For n upto 2, it returns 1 but after that the loop runs for every value.

for (3,3)
sum = 1+1

3 --> 2

for (3,4)
sum = 1+1
elem1, elem2 = elem2, sum

sum = 2+1

4--> 3

...

for (3,5)
...
for (3,6)
...
...

for(3,9)

This continues.
So the loop is not executed only once but everytime n changes.