code: def _get_shard_names(self, args):
          
          if 'sharded' in args and args['sharded']:
              if len(args['sharded']) == 1:
                  try:
                      # --sharded was a number, name shards shard01, shard02,
                      # ... (only works with replica sets)
                      n_shards = int(args['sharded'][0])
                      shard_names = ['shard%.2i'
                                     % (i + 1) for i in range(n_shards)]
                  except ValueError:
                      # --sharded was a string, use it as name for the one shard
                      shard_names = args['sharded']
              else:
                  shard_names = args['sharded']
          else:
              shard_names = [None]
          return shard_names
docs: Get the shard names based on the self.args['sharded'] parameter.
  
          If it's a number, create shard names of type shard##, where ## is a
          2-digit number. Returns a list [None] if no shards are present.