message: Simplify code for TensorListConcatLists shape inference
diff: @@ -590,18 +590,17 @@ REGISTER_OP("TensorListConcatLists")
  auto* handle_data_a = c->input_handle_shapes_and_types(0);
  auto* handle_data_b = c->input_handle_shapes_and_types(1);
  - if ((handle_data_a == nullptr || handle_data_a->empty()) &&
  - (handle_data_b == nullptr || handle_data_b->empty())) {
  + bool handle_data_a_nonempty = handle_data_a && !handle_data_a->empty();
  + bool handle_data_b_nonempty = handle_data_b && !handle_data_b->empty();
  + if (!(handle_data_a_nonempty || handle_data_b_nonempty)) {
  c->set_output_handle_shapes_and_types(
  0, {{c->UnknownShape(), element_dtype}});
  return Status::OK();
  }
  shape_inference::ShapeAndType list_shape_type_a =
  - (handle_data_a && !handle_data_a->empty()) ? handle_data_a->at(0)
  - : handle_data_b->at(0);
  + handle_data_a_nonempty ? handle_data_a->at(0) : handle_data_b->at(0);
  const shape_inference::ShapeAndType& list_shape_type_b =
  - (handle_data_b && !handle_data_b->empty()) ? handle_data_b->at(0)
  - : handle_data_a->at(0);
  + handle_data_b_nonempty ? handle_data_b->at(0) : handle_data_a->at(0);
  if (list_shape_type_a.dtype != element_dtype) {
  return errors::InvalidArgument("input_a.type != element_dtype: ",
  DataTypeString(list_shape_type_a.dtype),
  