docs: def expect_regex(self, pattern, timeout=3, regex_options=0):
          """Wait for a match to the regex in *pattern* to appear on the stream.
  
          Waits for input matching the regex *pattern* for up to *timeout*
          seconds. If a match is found, a :class:`RegexMatch` result is returned.
          If no match is found within *timeout* seconds, raise an
          :class:`ExpectTimeout` exception.
  
          :param pattern: The pattern to search for, as a single compiled regex
              or a string that will be processed as a regex.
          :param float timeout: Timeout in seconds.
          :param regex_options: Options passed to the regex engine.
          :return: :class:`RegexMatch` if matched, None if no match was found.
          """
          return self.expect(RegexSearcher(pattern, regex_options), timeout)