docs: def _lazy_re_compile(regex, flags=0):
      """Lazily compile a regex with flags."""
      def _compile():
          # Compile the regex if it was not passed pre-compiled.
          if isinstance(regex, str):
              return re.compile(regex, flags)
          else:
              assert not flags, "flags must be empty if regex is passed pre-compiled"
              return regex
      return SimpleLazyObject(_compile)