Stuck on this error message...

```
File "python", line 50
return average(results)
^
SyntaxError: invalid syntax
```

Why is this an invalid syntax when it's defined in my code below?

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