Hi. I'm totally stuck and had no idea what to do next. Can anyone please help me? My code below:

```
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(grades)
variance = 0
for score in scores:
n = (average - score) ** 2.0
total = variance + n
result = total / len(scores)
return result
print (grades_variance(grades))
```