Getting "students" is undefined for some reason ..... what's wrong ???

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