python clases relationship

# -*- coding: utf-8 -*-

class Pupil(object):

    def __init__(self, **kargs):
        self.name = kargs["name"]

    def set_group(self, group):
        self.group = group

class Teacher(object):

    def __init__(self, name, subjects):
        self.name = name
        self.subjects = subjects

class ClassRoom(object):

    def __init__(self, slug):
        self.slug = slug

class Lesson(object):

    def __init__(self, subject, classroom, teacher, group):
        self.subject = subject
        self.classroom = classroom
        self.teacher = teacher
        self.group = group
        self.parts = {}

    def set_part(self, name, materials):
        self.parts[name] = materials

    def provide_part(self, name):
        print "Lesson part:", name
        print self.parts[name]["text"]
        print "----------------"

    def __del__(self):
        print "Lesson", self.subject, "finished"
        print "Students lectured:"
        for person in self.group.pupils:
            print person.name.rjust(18)

class Group(object):

    def __init__(self, name, *args):
        self.name = name
        self.pupils = args
        for pupil in args:
            pupil.set_group(self)

# Приклад використання зв’язків

t = Teacher("Roman M. Kos", ["python basics"])
students = [
    Pupil(name="Kostiantyn"),
    Pupil(name="Sasha"),
    Pupil(name="Mykyta")
]
g = Group("independent students", *students)
cr = ClassRoom("godocoworking")
l = Lesson(subject="python classes", classroom=cr, teacher=t, group=g)

# Робота з даними і імітація реального процесу

l.set_part("introduction", {"text": "Introduction to python classes..."})
l.set_part("core", {"text": "Clases are...."})
l.set_part("q&a", {"text": "Now i am answering to given questions"})
l.set_part("ending", {"text": "Ok, now the time of homework instructions"})

l.provide_part("introduction")
l.provide_part("core")
l.provide_part("q&a")
l.provide_part("ending")

del l