-spec delete_world(binary()) -> ok.

-spec handle_call(term(), gen_server:from(), map()) -> {reply, term(), map()}.

-spec handle_cast(term(), map()) -> {noreply, map()}.

-spec handle_info(term(), map()) -> {noreply, map()}.

-spec init([]) -> {ok, map()}.

-spec load_snapshot(binary(), {integer(), integer()}) ->
                       {ok, map()} | {error, not_found} | {error, term()}.

-spec load_snapshots(binary()) -> {ok, map()} | {error, term()}.

-spec snapshot(map()) -> ok.

-spec snapshot_sync(map()) -> ok.

-spec start_link() -> gen_server:start_ret().