code: def down_sample(point_cloud, voxel_sz):
      """Quantize point cloud by voxel_size
      Returns kept indices
  
      Args:
          all_points: np.array (n, 3) float
          voxel_sz: float
      Returns:
          indices: (m, ) int
      """
      coordinates = np.round(point_cloud / voxel_sz).astype(np.int32)
      _, indices = np.unique(coordinates, axis=0, return_index=True)
      return indices
  
label_desc: Use image node_id 1 for calling a global function with example usage: down_sample(point_cloud, voxel_sz) and returns: indices