What is the problem this code. What the solution to this error?

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