code: def _read_header(self):
      header = self._fp.read(LEVELDBLOG_HEADER_LEN)
      assert (
          len(header) == LEVELDBLOG_HEADER_LEN
      ), "header is {} bytes instead of the expected {}".format(
          len(header), LEVELDBLOG_HEADER_LEN
      )
      ident, magic, version = struct.unpack("<4sHB", header)
      if ident != strtobytes(LEVELDBLOG_HEADER_IDENT):
          raise Exception("Invalid header")
      if magic != LEVELDBLOG_HEADER_MAGIC:
          raise Exception("Invalid header")
      if version != LEVELDBLOG_HEADER_VERSION:
          raise Exception("Invalid header")
      self._index += len(header)
  
imports: import logging
  import os
  import struct
  import zlib
  from typing import TYPE_CHECKING, Optional, Tuple
  import wandb
label_desc: Use image node_id 11 for calling the DataStore obj's underlying member method code with example usage: obj._read_header() without return types