old_contents: from django.db import models
  from schools.models import School
  
  # Create your models here.
  
  class School(models.Model):
  
      name = models.CharField(max_length=254, db_index=True, null=False, blank=False)
      courses = models.ManyToManyField(Course, null=True, blank=True)
  
new_contents: from django.db import models
  from courses.models import Course
  
  # Create your models here.
  
  class School(models.Model):
  
      name = models.CharField(max_length=254, db_index=True, null=False, blank=False)
      courses = models.ManyToManyField(Course, null=True, blank=True)
  
subject: fix to fix