```
number = raw_input("Enter a number")
def digit_sum(n):
total = 0
for i in str(n):
total += int(i)
print total
digit_sum(number)
```

When I run this I get this error

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

But when I enter 434 I get 11