new_contents: from django.core.management.base import NoArgsCommand
  
  from django.contrib.auth.models import User
  from zephyr.models import Zephyr, UserProfile, ZephyrClass, Recipient
  from django.contrib.sessions.models import Session
  
  class Command(NoArgsCommand):
      help = "Clear only tables we change: zephyr + sessions"
  
      def handle_noargs(self, **options):
          for klass in [Zephyr, ZephyrClass, UserProfile, User, Recipient]:
              klass.objects.all().delete()
          Session.objects.all().delete()
  
          self.stdout.write("Successfully cleared the database.\n")
  
subject: Add a 'clear_db' management command to drop our tables (zephyr + sessions).