code: def scan_record(self):
      assert self._opened_for_scan, "file not open for scanning"
      # TODO(jhr): handle some assertions as file corruption issues
      # assume we have enough room to read header, checked by caller?
      header = self._fp.read(LEVELDBLOG_HEADER_LEN)
      if len(header) == 0:
          return None
      assert (
          len(header) == LEVELDBLOG_HEADER_LEN
      ), "record header is {} bytes instead of the expected {}".format(
          len(header), LEVELDBLOG_HEADER_LEN
      )
      fields = struct.unpack("<IHB", header)
      checksum, dlength, dtype = fields
      # check len, better fit in the block
      self._index += LEVELDBLOG_HEADER_LEN
      data = self._fp.read(dlength)
      checksum_computed = (
          zlib.crc32(data, self._crc[dtype]) & 0xFFFFFFFF
      )
      assert (
          checksum == checksum_computed
      ), "record checksum is invalid, data may be corrupt"
      self._index += dlength
      return dtype, 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 8 for calling the DataStore obj's underlying member method code with example usage: obj.scan_record() and returns: dtype,  data, None