class_docstr: A subclass of :class:`Sphinx` that runs on the test root, with some
  better default values for the initialization parameters.
code: def __repr__(self) -> str:
      return f"<{self.__class__.__name__} buildername={self.builder.name!r}>"
  
imports: from __future__ import annotations
  import contextlib
  import os
  import re
  import sys
  import warnings
  from typing import IO, TYPE_CHECKING, Any
  from xml.etree import ElementTree
  from docutils import nodes
  from sphinx import application
label_desc: Use image node_id 3 for calling the SphinxTestApp obj's underlying member method code with example usage: obj.__repr__() and returns: str, self, str, self, str