docstr: Configuration option type for Sphinx.
  
  The type is intended to be immutable; changing the field values
  is an unsupported action.
  No validation is performed on the values, though consumers will
  likely expect them to be of the types advertised.
  The old tuple-based interface will be removed in Sphinx 9.
code: def __init__(
      self,
      default: Any,
      rebuild: _ConfigRebuild,
      valid_types: _OptValidTypes,
  ) -> None:
      """Configuration option type for Sphinx.
  
      The type is intended to be immutable; changing the field values
      is an unsupported action.
      No validation is performed on the values, though consumers will
      likely expect them to be of the types advertised.
      The old tuple-based interface will be removed in Sphinx 9.
      """
      super().__setattr__("default", default)
      super().__setattr__("rebuild", rebuild)
      super().__setattr__("valid_types", valid_types)
  
imports: from __future__ import annotations
  import sys
  import time
  import traceback
  import types
  import warnings
  from os import getenv, path
  from typing import TYPE_CHECKING, Any, Literal, NamedTuple, Union
  from sphinx.deprecation import RemovedInSphinx90Warning
  from sphinx.errors import ConfigError, ExtensionError
  from sphinx.locale import _, __
  from sphinx.util import logging
  from sphinx.util.osutil import fs_encoding
  from sphinx.util.typing import NoneType
label_desc: Use image node_id 1 to create a new _Opt object  with example: obj = _Opt(default, rebuild, valid_types)