code: def _maybe_read_file(filename):
      """Read the given file, if it exists.
  
      Args:
        filename: A path to a file.
  
      Returns:
        A string containing the file contents, or `None` if the file does
        not exist.
      """
      try:
          with open(filename) as infile:
              return infile.read()
      except IOError as e:
          if e.errno == errno.ENOENT:
              return None
  
imports: import base64
  import dataclasses
  import datetime
  import errno
  import json
  import os
  import subprocess
  import tempfile
  import time
  import typing
  from typing import Optional
  from tensorboard import version
  from tensorboard.util import tb_logging
label_desc: Use image node_id 12 for calling a global function with example usage: _maybe_read_file(filename) and returns: infile, None