def METHOD_NAME(self) -> ShmArray:
    if self._hist_shm_token is None:
        raise RuntimeError(
            'No shm token has been set for the history buffer?'
        )
    if (
        self._hist_shm is None
    ):
        self._hist_shm = attach_shm_array(
            token=self._hist_shm_token,
            readonly=True,
        )
    return self._hist_shm