code: def prepare_item(self, item):
      return item
  
imports: import os
  import random
  import sys
  from typing import Any, List
  from unittest import mock
  import lightning_cloud
  import numpy
  import pytest
  import torch
  from lightning import seed_everything
  from lightning.data.streaming import data_processor
  from lightning.data.streaming import functions
  from lightning.data.streaming.cache import Cache, Dir
  from lightning.data.streaming.data_processor import DataChunkRecipe, DataProcessor, DataTransformRecipe, _download_data_target, _get_item_filesizes, _map_items_to_workers_sequentially, _map_items_to_workers_weighted, _remove_target, _upload_fn, _wait_for_disk_usage_higher_than_threshold, _wait_for_file_to_exist
  from lightning.data.streaming.functions import LambdaDataTransformRecipe, map, optimize
  from lightning_cloud import resolver
  from lightning_utilities.core.imports import RequirementCache
label_desc: Use image node_id 2 for calling the CustomDataChunkRecipe obj's underlying member method code with example usage: obj.prepare_item(item) and returns: item