title: Add confirmation step to custom Django management/manage.py command
body: <p>I created the following custom management command following <a href="https://docs.djangoproject.com/en/1.10/howto/custom-management-commands/" rel="noreferrer">this tutorial</a>.</p>
  
  <pre><code>from django.core.management.base import BaseCommand, CommandError
  from django.contrib.auth.models import User
  
  from topspots.models import Notification
  
  
  class Command(BaseCommand):
      help = 'Sends message to all users'
  
      def add_arguments(self, parser):
          parser.add_argument('message', nargs='?')
  
      def handle(self, *args, **options):
          message = options['message']
          users = User.objects.all()
          for user in users:
              Notification.objects.create(message=message, recipient=user)
  
          self.stdout.write(
              self.style.SUCCESS(
                  'Message:\n\n%s\n\nsent to %d users' % (message, len(users))
              )
          )
  </code></pre>
  
  <p>It works exactly as I want it to, but I would like to add a confirmation step so that before the <code>for user in users:</code> loop you are asked if you really want to send message X to N users, and the command is aborted if you choose "no". </p>
  
  <p>I assume this can be easily done because it happens with some of the built-in management commands, but it doesn't seem to cover this in the tutorial and even after some searching and looking at the source for the built-in management commands, I have not been able to figure it out on my own.</p>