code: def _readback(self):
      temp = self._temp
      for name, substream in self._streams.items():
          substream.close()
  
          def gen():
              for f, offset, length in substream.blocks:
                  if f is None:
                      f = temp
                  f.seek(offset)
                  yield f.read(length)
  
          yield (name, gen)
      temp.close()
      self._tempstorage.delete_file(self._tempname)
  
imports: import errno
  import os
  import sys
  from threading import Lock
  from shutil import copyfileobj
  from whoosh.compat import BytesIO, memoryview_
  from whoosh.filedb.structfile import BufferFile, StructFile
  from whoosh.filedb.filestore import FileStorage, StorageError
  from whoosh.system import emptybytes
  from whoosh.util import random_name
label_desc: Use image node_id 3 for calling the CompoundWriter obj's underlying member method code with example usage: obj._readback() without return types