I keep getting the following error message "The program took too long to finish. Check your code for infinite loops

and try again". I thought that my loop was not infinite because n will eventually hit zero. Where did I go wrong?

```
def digit_sum(n):
n_sum = 0
while n != 0:
n_sum = n_sum + (n % 10)
n // 10
return n_sum
```