This is my code:

```
def digit_sum(n) :
str_n = str(n)
lst_n = list(str_n)
for i in lst_n:
numbers= []
integer = int(lst_n[i])
numbers.append(integer)
return sum(numbers)
```

error message says:

Oops, try again. Does your digit_sum function take exactly one argument (a positive integer)? Your code threw a "list indices must be integers, not str" error.

I thought I have successfully changed string in to list of integers, but the error messages says that I didn't.

I am so stuck. can anybody help me out with this?

`Replace this line with your code.`