old_contents: from django.db import models
  
  class ClassRoom(models.Model):
      number = models.CharField(max_length=4)
  
      def __unicode__(self):
          return unicode(self.number)
  
  class Lab(models.Model):
      name = models.CharField(max_length=10)
  
      def __unicode__(self):
          return unicode(self.name)
  
  class Dept(models.Model):
      name = models.CharField(max_length=10)
      allotted_rooms = models.ManyToManyField(ClassRoom)
      allotted_labs = models.ManyToManyField(Lab)
  
      def __unicode__(self):
          return unicode(self.name)
  
  class Employee(models.Model):
      name = models.CharField(max_length=30)
      salary = models.FloatField()
      dept = models.ForeignKey(Dept)
      manager = models.ForeignKey('Employee', null=True, blank=True)
  
      def __unicode__(self):
          return unicode(self.name)
  
  class Word(models.Model):
      word = models.CharField(max_length=15)
  
      def __unicode__(self):
          return unicode(self.word)
  
new_contents: from django.db import models
  
  class ClassRoom(models.Model):
      number = models.CharField(max_length=4)
  
      def __unicode__(self):
          return unicode(self.number)
  
  class Lab(models.Model):
      name = models.CharField(max_length=10)
  
      def __unicode__(self):
          return unicode(self.name)
  
  class Dept(models.Model):
      name = models.CharField(max_length=10)
      allotted_rooms = models.ManyToManyField(ClassRoom)
      allotted_labs = models.ManyToManyField(Lab)
  
      def __unicode__(self):
          return unicode(self.name)
  
  class Employee(models.Model):
      name = models.CharField(max_length=30)
      salary = models.FloatField()
      dept = models.ForeignKey(Dept)
      manager = models.ForeignKey('Employee', null=True, blank=True)
  
      def __unicode__(self):
          return unicode(self.name)
  
  class Word(models.Model):
      word = models.CharField(max_length=15)
  
      def __unicode__(self):
          return unicode(self.word)
  
  
  class School(models.Model):
  
      classes = models.ManyToManyField(ClassRoom)
  
subject: Add new testing model `School`