new_contents: 
  from typing import Any
  
  from argparse import ArgumentParser
  from confirmation.models import Confirmation, create_confirmation_link
  from zerver.lib.management import ZulipBaseCommand
  from zerver.lib.actions import create_stream_if_needed
  from zerver.models import MultiuseInvite, DefaultStream, DefaultStreamGroup
  
  
  class Command(ZulipBaseCommand):
      help = """
  Create default stream groups which the users can choose during sign up.
  
  ./manage.py create_default_stream_groups -s gsoc-1,gsoc-2,gsoc-3 -d "Google summer of code"  -r zulip
  """
  
      def add_arguments(self, parser):
          # type: (ArgumentParser) -> None
          self.add_realm_args(parser, True)
  
          parser.add_argument(
              '-s', '--streams',
              dest='streams',
              type=str,
              required=True,
              help='A comma-separated list of stream names.')
  
          parser.add_argument(
              '-d', '--default-stream-group',
              dest='default_stream_group',
              type=str,
              required=True,
              help='Name of the group you want to create.'
          )
  
      def handle(self, *args, **options):
          # type: (*Any, **Any) -> None
          realm = self.get_realm(options)
          assert realm is not None  # Should be ensured by parser
  
          streams = []
          stream_names = set([stream.strip() for stream in options["streams"].split(",")])
          for stream_name in set(stream_names):
              stream, _ = create_stream_if_needed(realm, stream_name)
              streams.append(stream)
  
          try:
              default_stream_group = DefaultStreamGroup.objects.get(name=options["default_stream_group"], realm=realm)
          except DefaultStreamGroup.DoesNotExist:
              default_stream_group = DefaultStreamGroup.objects.create(name=options["default_stream_group"], realm=realm)
          default_stream_group.streams = streams
          default_stream_group.save()
  
          default_stream_groups = DefaultStreamGroup.objects.all()
          for default_stream_group in default_stream_groups:
              print(default_stream_group.name)
              for stream in default_stream_group.streams.all():
                  print(stream.name)
  
subject: Create command for creating default stream groups.