code: def check_data_exists(data_files):
      """
      Check that the input data files exist. If the data_files is a list,
      we iteratively check for each file in the list.
      """
      if isinstance(data_files, list):
          return np.all([g_pathmgr.exists(item) for item in data_files])
      else:
          return g_pathmgr.exists(data_files)
  
imports: import json
  import logging
  import os
  from typing import List
  import numpy
  from iopath.common.file_io import g_pathmgr
  from vissl.data.datasets import get_coco_imgs_labels_info, get_voc_images_labels_info
  from vissl.utils.misc import get_json_data_catalog_file
  from vissl.utils.slurm import get_slurm_dir
label_desc: Use image node_id 3 for calling a global function with example usage: check_data_exists(data_files) and returns: np, g_pathmgr