class_docstr: Fragment from KITTI Odometry dataset
code: def len(self):
      return len(self)
  
imports: import numpy
  import os
  import os.path
  import torch
  from torch_geometric.data import Data
  from torch_points3d.datasets.registration.base_kitti import BaseKitti
  from torch_points3d.datasets.registration.utils import PatchExtractor
  from torch_points3d.metrics.registration_tracker import FragmentRegistrationTracker
  from torch_points3d.datasets.registration.base_siamese_dataset import BaseSiameseDataset
  from torch_points3d.datasets.registration.base_siamese_dataset import GeneralFragment
label_desc: Use image node_id 4 for calling the FragmentKitti obj's underlying member method code with example usage: obj.len() and returns: len