Why does the instructions tell you to make a new variable 'variance' after the function? Couldn't it be done without it. Following the instructions I get this code

```
grades = [100, 100, 90, 40, 80, 100, 85, 70, 90, 65, 90, 85, 50.5]
def print_grades(grades):
for grade in grades:
print grade
def grades_sum(grades):
total = 0
for grade in grades:
total += grade
return total
def grades_average(grades):
sum_of_grades = grades_sum(grades)
average = sum_of_grades / float(len(grades))
return average
def grades_variance(scores):
average = grades_average(scores)
variance = 0
for score in scores:
variance = (average - score) ** 2 + variance
return variance/len(scores)
def grades_std_deviation(variance):
return variance ** 0.5
variance = grades_variance(grades)
print grades_std_deviation(variance)
```

Can it be done like this:

```
grades = [100, 100, 90, 40, 80, 100, 85, 70, 90, 65, 90, 85, 50.5]
def print_grades(grades):
for grade in grades:
print grade
def grades_sum(grades):
total = 0
for grade in grades:
total += grade
return total
def grades_average(grades):
sum_of_grades = grades_sum(grades)
average = sum_of_grades / float(len(grades))
return average
def grades_variance(scores):
average = grades_average(scores)
variance = 0
for score in scores:
variance = (average - score) ** 2 + variance
return variance/len(scores)
def grades_std_deviation(variance):
variance = grades_variance(grades)
return variance ** 0.5
print grades_std_deviation(grades)
```

is there something I'm not seeing here?