code: def _protobuf_file_saver(ctx, filename, ext):
      logger.info("Saving {} as protobuf".format(filename))
      with get_file_handle_save(filename, ext) as f:
          f.write(ctx.proto.SerializeToString())
  
imports: import contextlib
  import io
  import os
  import re
  import zipfile
  from collections import OrderedDict
  from functools import partial
  import google.protobuf.text_format
  import h5py
  import nnabla
  import numpy
  from nnabla.logger import logger
  from nnabla.utils import nnabla_pb2
  from nnabla.utils.nnp_format import nnp_version
label_desc: Use image node_id 19 for calling a global function with example usage: _protobuf_file_saver(ctx, filename, ext) without return types