code: def __getitem__(self, key):
      return self.metadata[key]
  
imports: import os
  import re
  import collections
  from medicaltorch import transforms
  from tqdm import tqdm
  import numpy
  import nibabel
  from torch.utils.data import Dataset
  import torch
  from torch._six import string_classes, int_classes
  from PIL import Image
label_desc: Use image node_id 3 for calling the SampleMetadata obj's underlying member method code with example usage: obj.__getitem__(key) and returns: self