1.最后，print out the result of calling get_class_average with your students list.Your students should be[lloyd,alice,tyler].
2.然后，print the result of get_letter_grade for the class's average.

students = [lloyd,alice,tyler]
results = []
def get_class_average(students):
for student in students:
results.append(get_average(student))
print get_class_average(results)
print get_letter_grade(get_class_average(results))

8.part of the whole
def get_class_average(students):
results = []
for student in students:
results.append(get_average(student))
return average(results)
1.定义get_class_average,变量students
2.空列表results