code: def _write_header(self):
      data = struct.pack(
          "<4sHB",
          strtobytes(LEVELDBLOG_HEADER_IDENT),
          LEVELDBLOG_HEADER_MAGIC,
          LEVELDBLOG_HEADER_VERSION,
      )
      assert (
          len(data) == LEVELDBLOG_HEADER_LEN
      ), f"header size is {len(data)} bytes, expected {LEVELDBLOG_HEADER_LEN}"
      self._fp.write(data)
      self._index += len(data)
  
imports: import logging
  import os
  import struct
  import zlib
  from typing import TYPE_CHECKING, Optional, Tuple
  import wandb
label_desc: Use image node_id 10 for calling the DataStore obj's underlying member method code with example usage: obj._write_header() without return types