code: def test_dense(self):
      data = Data(
          pos=torch.randn((3, 1000, 3)), x=torch.randn((3, 3, 1000))
      )
      sampler = FPSSamplerToDense(num_to_sample=201)
      sampled_data, idx = sampler.sample(data, 3, "DENSE")
      self.assertEqual(sampled_data.pos.shape, (3, 201, 3))
      self.assertEqual(sampled_data.x.shape, (3, 3, 201))
  
file_path: torch-points3d/test/test_sampler.py
imports: import unittest
  import torch
  from torch_geometric.data import Data
  from torch_points3d.core.spatial_ops import FPSSampler, RandomSampler, RadiusNeighbourFinder, MultiscaleRadiusNeighbourFinder
  from torch_points3d.modules.VoteNet.dense_samplers import FPSSamplerToDense
label_desc: Use image node_id 1 for calling the TestFPStoDense obj's underlying member method code with example usage: obj.test_dense() without return types