code: def repair_docinfo_nuls(pdf):
      """If the DocumentInfo block contains NUL characters, remove them.
  
      If the DocumentInfo block is malformed, log an error and continue.
      """
      modified = False
      try:
          if not isinstance(pdf.docinfo, Dictionary):
              raise TypeError("DocumentInfo is not a dictionary")
          for k, v in pdf.docinfo.items():
              if isinstance(v, str) and b"\x00" in bytes(v):
                  pdf.docinfo[k] = bytes(v).replace(b"\x00", b"")
                  modified = True
      except TypeError:
          # TypeError can also be raised if dictionary items are unexpected types
          log.error(
              "File contains a malformed DocumentInfo block - continuing anyway."
          )
      return modified
  
imports: from __future__ import annotations
  import logging
  import os
  from datetime import datetime, timezone
  from pathlib import Path
  from typing import Any
  from pikepdf import Dictionary, Name, Pdf
  from pikepdf import __version__
  from pikepdf.models.metadata import PdfMetadata, encode_pdf_date
  from ocrmypdf._jobcontext import PdfContext
  from ocrmypdf._version import PROGRAM_NAME
  from ocrmypdf._version import __version__
  from ocrmypdf.languages import iso_639_2_from_3
label_desc: Use image node_id 3 for calling a global function with example usage: repair_docinfo_nuls(pdf) and returns: modified