How is Everybody Doing?

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

I don't see any error there so expect program to execute successfully. please help

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