    bi::managed_external_buffer::handle_t handle)
{
  AllocatedSharedMemory<StringShm> string_container_shm =
      shm_pool->Load<StringShm>(handle);
  AllocatedSharedMemory<char> string_shm =
      shm_pool->Load<char>(string_container_shm.data_->data);

  return std::unique_ptr<PbString>(
      new PbString(string_container_shm, string_shm));
}

std::unique_ptr<PbString>