code: def _write_actual_size(self):
      # we need to reopen the SharedMemory object as the size
      # of the original one is less than the actual size.
      actual_shm = SharedMemory(name=self._object_id)
      actual_shm.buf[-8:] = _qword_pack.pack(self._size)
  
imports: import asyncio
  import os
  import random
  import struct
  import sys
  from string import ascii_letters, digits
  from typing import Any, Dict, List, Tuple, Optional
  from dataclasses import dataclass
  from ..serialization import AioSerializer, AioDeserializer
  from ..utils import implements, dataslots
  from .base import StorageBackend, StorageLevel, ObjectInfo, register_storage_backend
  from .core import BufferWrappedFileObject, StorageFileObject
label_desc: Use image node_id 2 for calling the SharedMemoryFileObject obj's underlying member method code with example usage: obj._write_actual_size() without return types