code: def __getitem__(self, index):
      img, _ = self.dataset[index]
  
      img = self.transform_train(img)
  
      source = None
      target = None
      if self.transform_source is not None:
          source = self.final_transform(self.transform_source(img))
      if self.transform_target is not None:
          target = self.final_transform(self.transform_target(img))
  
      if source is None:
          img = self.final_transform(img)
  
      v = {"id": index, self.key: source if source is not None else img}
      if target is not None:
          v["target"] = target
  
      if self.is_compute_mask:
          if self.mask_length == 1:
              mask = compute_block_mask_1d(
                  shape=(self.clone_batch, self.patches),
                  mask_prob=self.mask_prob,
                  mask_length=self.mask_length,
                  mask_prob_adjust=self.mask_prob_adjust,
                  inverse_mask=self.inverse_mask,
                  require_same_masks=True,
              )
          else:
              mask = compute_block_mask_2d(
                  shape=(self.clone_batch, self.patches),
                  mask_prob=self.mask_prob,
                  mask_length=self.mask_length,
                  mask_prob_adjust=self.mask_prob_adjust,
                  inverse_mask=self.inverse_mask,
                  require_same_masks=True,
                  expand_adjcent=self.expand_adjacent,
                  mask_dropout=self.mask_dropout,
                  non_overlapping=self.non_overlapping,
              )
  
          v["precomputed_mask"] = mask
  
      return v
  
imports: from functools import partial
  import logging
  import math
  import random
  import time
  import numpy
  import os
  import torch
  from torchvision import datasets, transforms
  from .path_dataset import PathDataset
  from fairseq.data import FairseqDataset
  from fairseq.data.data_utils import compute_block_mask_1d, compute_block_mask_2d
  from shutil import copyfile
label_desc: Use image node_id 2 for calling the MaeImageDataset obj's underlying member method code with example usage: obj.__getitem__(index) and returns: v