code: def write_transaction(self):
      class WriteTransaction:
          def __enter__(self2):
              self._lock.writer_lock.acquire()
  
          def __exit__(self2, exc_type, exc_val, exc_tb):
              if exc_type:
                  # When an error happens in the middle of a write
                  # transaction we must roll it back and clear the cache
                  # because the writer may have partially modified the Nodes
                  self._wal.rollback()
                  self._cache.clear()
              else:
                  self._wal.commit()
              self._lock.writer_lock.release()
  
      return WriteTransaction()
  
imports: import enum
  import io
  from logging import getLogger
  import os
  import platform
  from typing import Union, Tuple, Optional
  import cachetools
  import rwlock
  from .node import Node, FreelistNode
  from .const import ENDIAN, PAGE_REFERENCE_BYTES, OTHERS_BYTES, TreeConf, FRAME_TYPE_BYTES
label_desc: Use image node_id 7 for calling the FileMemory obj's underlying member method code with example usage: obj.write_transaction() and returns: WriteTransaction