```
y = []
def digit_sum(n):
n = str(n)
for x in n:
x = int(x)
y.append(x)
for z in y:
z = sum(y)
return z
print digit_sum(434)
```

The error says: Oops, try again. Your function fails on digit_sum(434). It returns 22 when it should return 11.

However, in fact the function returns exactly 11.