title: How to make a Django custom management command argument not required?
body: <p>I am trying to write a custom management command in django like below-</p>
  
  <pre><code>class Command(BaseCommand):
  
      def add_arguments(self, parser):
          parser.add_argument('delay', type=int)
  
      def handle(self, *args, **options):
          delay = options.get('delay', None)
          print delay
  </code></pre>
  
  <p>Now when I am running <code>python manage.py mycommand 12</code> it is printing 12 on console. Which is fine.</p>
  
  <p>Now if I try to run <code>python manage.py mycommand</code> then I want that, the command prints 21 on console by default. But it is giving me something like this-</p>
  
  <pre><code>usage: manage.py mycommand [-h] [--version]
                             [-v {0,1,2,3}]
                             [--settings SETTINGS]
                             [--pythonpath PYTHONPATH]
                             [--traceback]
                             [--no-color]
                             delay
  </code></pre>
  
  <p>So now, how should I make the command argument "not required" and take a default value if value is not given?</p>