code: def read_string_file(file_name: str) -> str:
      """Reads a string from a file."""
      if not fileio.exists(file_name):
          msg = "{} does not exist".format(file_name)
          raise FileNotFoundError(msg)
      return fileio.open(file_name).read()
  
imports: import os
  import re
  import tempfile
  from typing import List, TypeVar, Iterable
  from tfx.dsl.io import fileio
  from google.protobuf import json_format
  from google.protobuf import text_format
  from google.protobuf.message import Message
label_desc: Use image node_id 15 for calling a global function with example usage: read_string_file(file_name) and returns: fileio