code: def test_sphere(self):
      sphere_sampling = SphereSampling(0.1, [0, 0, 0])
      sampled = sphere_sampling(self.data)
  
      self.assertIn(SphereSampling.KDTREE_KEY, self.data)
      self.assertEqual(len(sampled.labels), 1)
      self.assertEqual(sampled.labels[0], 2)
  
file_path: torch-points3d/test/test_sphere_sampling.py
imports: import os
  import sys
  import unittest
  import numpy
  import torch
  from torch_geometric.data import Data
  from torch_points3d.core.data_transform.transforms import RandomSphere, SphereSampling
label_desc: Use image node_id 2 for calling the TestSphereSampling obj's underlying member method code with example usage: obj.test_sphere() without return types