text: import numpy as np
  
  from second.core.voxel_generator import VoxelGenerator
  from second.protos import voxel_generator_pb2
  
  
  def build(voxel_config):
      """Builds a tensor dictionary based on the InputReader config.
  
      Args:
          input_reader_config: A input_reader_pb2.InputReader object.
  
      Returns:
          A tensor dict based on the input_reader_config.
  
      Raises:
          ValueError: On invalid input reader proto.
          ValueError: If no input paths are specified.
      """
      if not isinstance(voxel_config, (voxel_generator_pb2.VoxelGenerator)):
          raise ValueError('input_reader_config not of type '
                           'input_reader_pb2.InputReader.')
      voxel_generator = VoxelGenerator(
          voxel_size=list(voxel_config.voxel_size),
          point_cloud_range=list(voxel_config.point_cloud_range),
          max_num_points=voxel_config.max_number_of_points_per_voxel,
          max_voxels=20000)
      return voxel_generator
  