code: def __getitem__(self, idx):
      return self.get_fragment(idx)
  
imports: import numpy
  import os
  import os.path
  import torch
  import json
  from torch_points3d.datasets.base_dataset import BaseDataset
  from torch_points3d.datasets.registration.basetest import Base3DMatchTest
  from torch_points3d.datasets.registration.basetest import SimplePatch
  from torch_points3d.datasets.registration.utils import PatchExtractor
  from torch_points3d.datasets.registration.detector import RandomDetector
  from torch_points3d.datasets.registration.pair import Pair, MultiScalePair
  from torch_points3d.datasets.registration.utils import tracked_matches
  from torch_points3d.datasets.registration.base_siamese_dataset import GeneralFragment
  from torch_points3d.datasets.registration.base_siamese_dataset import BaseSiameseDataset
label_desc: Use image node_id 2 for calling the TestPair3DMatch obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: self