old_contents: """
  Management command to cross-publish announcements on Twitter.
  """
  
  from django.core.management.base import NoArgsCommand
  
  from ...models import AnnouncementTwitterCrossPublication
  
  
  class Command(NoArgsCommand):
      """
      A management command which cross-publish on Twitter any pending announcements
      currently published on the site but not on Twitter yet. Simply call the ``publish_pending_announcements``of
      the ``AnnouncementTwitterCrossPublication`` class to do the job.
      """
  
      help = "Cross-publish pending announcements on Twitter"
  
      def handle_noargs(self, **options):
          """
          Command handler.
          :param options: Not used.
          :return: None.
          """
          AnnouncementTwitterCrossPublication.objects.publish_pending_announcements()
  
new_contents: """
  Management command to cross-publish announcements on Twitter.
  """
  
  from django.core.management.base import NoArgsCommand
  
  from apps.dbmutex import MutexLock,AlreadyLockedError, LockTimeoutError
  
  from ...models import AnnouncementTwitterCrossPublication
  
  
  class Command(NoArgsCommand):
      """
      A management command which cross-publish on Twitter any pending announcements
      currently published on the site but not on Twitter yet. Simply call the ``publish_pending_announcements``of
      the ``AnnouncementTwitterCrossPublication`` class to do the job. Use the ``dbmutex`` app to avoid concurrent
      execution of the code.
      """
  
      help = "Cross-publish pending announcements on Twitter"
  
      def handle_noargs(self, **options):
          """
          Command handler.
          :param options: Not used.
          :return: None.
          """
  
          # Lock a critical section of code
          try:
              with MutexLock('twitter_announcements'):
  
                  # Do the job
                  AnnouncementTwitterCrossPublication.objects.publish_pending_announcements()
  
          except AlreadyLockedError:
              print('Could not obtain lock (another instance of the script running?)')
  
          except LockTimeoutError:
              print('Task completed but the lock timed out')
  
subject: Add mutex to the "tweetannouncement" management command.