class_docstr: A class for loading images from a tar archive or a regular folder.
  
  This class provides functionality to open and read images from either a tar archive
  (.tar file) or a standard directory with image files. It builds an index of images
  if the source is a tar archive for efficient access.
  
  Attributes:
      image_folder (str): The path to the tar archive or image folder.
      tar_index (dict): A dictionary that maps file names to their tarfile member
                        objects if the image source is a tar archive.
  
  Methods:
      __init__(self, image_folder): Initializes the loader with the specified image folder.
      build_index(self): Builds an index of image file names and their corresponding
                         tarfile member objects for a tar archive.
      open_image(self, file_name): Opens and returns an image by its file name. The image
                                   is returned as an RGB PIL Image object.
code: def __init__(self, image_folder):
      self.image_folder = image_folder
      self.tar_index = {}
      if self.image_folder.endswith(".tar"):
          self.build_index()
  
imports: import copy
  import json
  import logging
  import os
  import re
  import tarfile
  from dataclasses import dataclass
  from typing import Any, Dict, List, Sequence, Union
  import torch
  import torch.nn.functional
  import transformers
  from einops import rearrange
  from omegaconf import DictConfig
  from PIL import Image
  from torch.utils.data import Dataset, default_collate
  from transformers import CLIPImageProcessor
  import nemo.collections.multimodal.data.neva.conversation
  from nemo.collections.nlp.modules.common.megatron.utils import get_ltor_masks_and_position_ids
label_desc: Use image node_id 1 to create a new TarOrFolderImageLoader object  with example: obj = TarOrFolderImageLoader(image_folder)