Why is this not working?

```
lloyd = {
"name": "Lloyd",
"homework": [90.0, 97.0, 75.0, 92.0],
"quizzes": [88.0, 40.0, 94.0],
"tests": [75.0, 90.0]
}
alice = {
"name": "Alice",
"homework": [100.0, 92.0, 98.0, 100.0],
"quizzes": [82.0, 83.0, 91.0],
"tests": [89.0, 97.0]
}
tyler = {
"name": "Tyler",
"homework": [0.0, 87.0, 75.0, 22.0],
"quizzes": [0.0, 75.0, 78.0],
"tests": [100.0, 100.0]
}
# Add your function below!
def average(numbers):
total=sum(numbers)
total=float(total)
return total/len(numbers)
def get_average (student):
homework=0.1*average(student["homework"])
quizzes=0.3*average(student["quizzes"])
tests=0.6*average(student["tests"])
return homework+quizzes+tests
def get_letter_grade(score):
if score >=90:
return "A"
elif score >=80:
return "B"
elif score >=70:
return "C"
elif score >=60:
return "D"
else:
return "F"
get_letter_grade(lloyd)
print get_letter_grade
def get_class_average(students):
#Finds the weighted averages of the students in the class list, and then finds the average of those results to give the class weighted average
results = []
for student in students:
results.append(get_average(student))
return average(results)
print get_class_average([lloyd, alice, tyler])
print get_letter_grade(get_class_average)
```