This gives me this error message

get_class_average([alice]) resulted in an error: list indices must be integers, not str

Could someone explain to me what my code is attempting to do?

```
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):
for i in student:
homework = average(student['homework'])
quizzes = average(student['quizzes'])
tests = average(student['tests'])
return homework*.1 + quizzes*.3 + tests*.6
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(get_average(lloyd))
def get_class_average(students):
results = []
for t in students :
results = get_average(students)
results.append
return average(results)
```