code: def handle(self, *args, **options):
          
          cron_classes = options['cron_classes']
          if cron_classes:
              cron_class_names = cron_classes
          else:
              cron_class_names = getattr(settings, 'CRON_CLASSES', [])
  
          try:
              crons_to_run = [get_class(x) for x in cron_class_names]
          except Exception:
              error = traceback.format_exc()
              self.stdout.write('Make sure these are valid cron class names: %s\n%s' % (cron_class_names, error))
              return
  
          for cron_class in crons_to_run:
              run_cron_with_cache_check(
                  cron_class,
                  force=options['force'],
                  silent=options['silent']
              )
  
          clear_old_log_entries()
          close_old_connections()
docs: Iterates over all the CRON_CLASSES (or if passed in as a commandline argument)
          and runs them.