code: def files_exist(files):
      """
      taken from https://pytorch-geometric.readthedocs.io/en/latest/_modules/torch_geometric/data/dataset.html#Dataset
      """
  
      return all([osp.exists(f) for f in files])
  
imports: import collections
  import errno
  import numpy
  import os
  import os.path
  import torch
  from torch_geometric.data import Data
  from torch_points_kernels.points_cpu import ball_query
  import imageio
  from tqdm.auto import tqdm
  from torch_points3d.core.data_transform import GridSampling3D, SaveOriginalPosId
  from torch_geometric.transforms import Compose
  import torch_points3d.datasets.registration.fusion
  from torch_cluster import fps
label_desc: Use image node_id 2 for calling a global function with example usage: files_exist(files) and returns: all