new_contents: import os
  from datetime import time
  
  from django.db import migrations
  
  def add_timetable(apps, schema_editor):
      TimeTable = apps.get_model('app', 'TimeTable')
  
      for weekday in range(1, 8):
          for start in (8, 10, 13, 15, 17, 19):
              end = start + 2
              time_table = TimeTable(weekday=weekday, start=time(start),
                      end=time(end))
              time_table.save()
  
  class Migration(migrations.Migration):
      dependencies = [
          ('app', '0001_initial'),
          ('app', '0002_subject'),
          ('app', '0003_region'),
          ('app', '0004_grade'),
          ('app', '0005_gradesubject'),
          ('app', '0006_level'),
          ('app', '0007_role'),
      ]
  
      operations = [
          migrations.RunPython(add_timetable),
      ]
  
subject: Initialize time table data.