code: def digitally_signed(acroform, outdir):
      out = outdir / "acroform_signed.pdf"
      with pikepdf.open(acroform) as pdf:
          pdf.Root.AcroForm.SigFlags = 3
          pdf.save(out)
      yield out
  
file_path: OCRmyPDF/tests/test_acroform.py
imports: from __future__ import annotations
  import logging
  import pikepdf
  import pytest
  import ocrmypdf
  from .conftest import check_ocrmypdf
label_desc: Use image node_id 4 for calling a global function with example usage: digitally_signed(acroform, outdir) without return types