digit_sum

Oops, try again. Your function fails on digit_sum(434). It returns None when it should return 11.

For integer 1234, returns 10, still says the above error

My code looks correct and does what I expect, however it still returns an error message. I have tested this for a bunch of other integers and the sums of the digits are correct, but still errors.

```
def digit_sum(n):
string = str(n)
lst = []
for number in string:
lst.append(number)
count = 0
for i in lst:
count += int(i)
print count
digit_sum(1234)
```