class_docstr: Test helper for content.opf and toc.ncx
class_docstr_tok: ["Test","helper","for","content.opf","and","toc.ncx"]
code: def find(self, match):
      ret = self.tree.find(match, namespaces=self.namespaces)
      if ret is not None:
          return self.__class__(ret)
      else:
          return ret
  
imports: import os
  import subprocess
  from pathlib import Path
  from subprocess import CalledProcessError
  from xml.etree import ElementTree
  import pytest
  from sphinx.builders.epub3 import _XML_NAME_PATTERN
label_desc: Use image node_id 3 for calling the EPUBElementTree obj's underlying member method code with example usage: obj.find(match) and returns: self, ret