python - How to use nested *Nested Dictionaries* -

so code neatest if able nest dictionaries. questions are:

1. are nested dictionaries real thing? (is possible?)
2. how set them up?
3. how value of sub-dictionary key?

here of code trying use. please tell me correct format is, , might wrong... thanks!

student.alice = {             student.alice.math = {                 'math1'= 100                 'math2'= 98                 'math3' = 89                 'math4' = 91                 'math5' = 77                 'math6' = 90                 'math7' = 82                 'math8' = 100                 'math9' = 79                 'math10' = 100                 }             student.alice.english = {                 'english1' = 100                 'english2' = 97                 'english3' = 98                 'english4' = 88                 'english5' = 94                 'english6' = 95                 'english7' = 98                 'english8' = 82                 'english9' = 84                 'english10' = 99                 }             student.alice.science = {                 'science1' = 78                 'science2' = 89                 'science3' = 88                 'science4' = 92                 'science5' = 92                 'science6' = 91                 'science7' = 93                 'science8' = 88                 'science9' = 99                 'science10' = 87                 }             student.alice.french = {                 'french1' = 100                 'french2' = 100                 'french3' = 99                 'french4' = 104                 'french5' = 103                 'french6' = 97                 'french7' = 94                 'french8' = 93                 'french9' = 75                 'french10' = 93                 }             } 

nested dictionaries going lead world of pain in future. highly suggest learning object oriented programming, , classes. below not-working-but-headed-in-the-right-direction example.

class assignment(dict):     '''this inherits dict, student key, grade score'''     def __init__(self, name, max_score):         self.name = name         self.max_score = max_score         self.grades = {} # used store students , grades.      def __getitem__(self, student):         # we're overriding getitem, because default 0 if student doesn't turn in work         if student in self:             return dict.__getitem__(self, student)         return 0.0  class gradebook(dict):     '''a gradebook dict of assignments'''     def get_max_score(self):         return sum(assignment.max_score assignment in self.values())      def get_percentage(self, student):         return 100.0 * sum(assignment[student] assignment in self.values()) / self.get_max_score()  class course(object):     def __init__(self, name, time, teacher, students):         self.name = name         self.time = time # can teach multiple courses same name, not @ same time         self.teacher = teacher         self.students = students         self.grade_book = gradebook()      def add_assignment(self, assignemnt):         self.grade_book.append(assignment)  class person(object):     def __init__(self, first, last):         self.first = first         self.last = last     def __repr__(self):         return '<{} {} {}>'.format(self.__class__.__name__, self.first, self.last)   class student(person):     '''a student person...'''   class teacher(person):     '''a teacher person...'''