the exercise was:

Takes in a list of scores, scores

Computes the sum of the scores

Returns the computed sum

Call the newly created grades_sum() function with the list of grades and print the result.

Oops, try again. It looks like your grades_sum function doesn't properly compute the sum of all the grades! It returned None instead of 188 for grades_sum([36, 1, 95, 56])

to print out the sum, which it did but when it tested my code (as in the error message) it returned none.

```
grades = [100, 100, 90, 40, 80, 100, 85, 70, 90, 65, 90, 85, 50.5]
def grades_sum(x):
total=0
for i in x:
total= total + i
print total
grades_sum(grades)
```