code: def rst_big_header(s):
      return f"{s}\n{'='*len(s)}\n"
  
imports: import collections
  import contextlib
  import itertools
  import json
  import os
  import typing
  from pytext.config import ConfigBase, ExportConfig, PyTextConfig
  from pytext.config.component import Registry
  from pytext.config.serialize import config_to_json
  from pytext.utils.file_io import PathManager
  from sphinx.ext.napoleon import GoogleDocstring
  from sphinx.pycode import ModuleAnalyzer
label_desc: Use image node_id 8 for calling a global function with example usage: rst_big_header(s) and returns: s, str, unknown, str