Oops, try again. One of the following is missing or broken when we tried to use it: alice, lloyd, tyler, students, get_class_average, get_letter_grade

Hello! I get the following printed:

83.8666666667

B

None

but for some reason I still get that pesky error. My code is the same as the last exercise, I only added the last 3 lines. It prints the correct values and I have no clue where sth went wrong. Thank you for your help in advance!

```
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)
total /= len(numbers)
return total
def get_average(student):
homework = average(student["homework"])
quizzes = average(student["quizzes"])
tests = average(student["tests"])
wavg = (float(homework)*0.1 + float(quizzes)*0.3 + float(tests)*0.6)
return wavg
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"
students=[alice, lloyd, tyler]
def get_class_average(students):
results=[]
for student in students:
results.append(get_average(student))
return average(results)
average=get_class_average(students)
print average
print get_letter_grade(average)
```