code: def dump_normals(dataset_dir, data_dir, dataset, root=None, compress=True):
      
      if root is None:
          root = {}
      normals = dataset.GetPointData().GetNormals()
      if normals:
          dumped_array = dump_data_array(dataset_dir, data_dir, normals, {}, compress)
          root['pointData']['activeNormals'] = len(root['pointData']['arrays'])
          root['pointData']['arrays'].append({'data': dumped_array})
docs: dump vtkjs normal vectors