I have triple checked my code and have run it in repl.it and it works fine. but Codecademy keeps spinning and spinning as if in a loop when I run it. Is this a bug or am I completely off???

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