code: def _parse_documentclass(self):
          
          command = LatexCommand(
              'documentclass',
              {'name': 'options', 'required': False, 'bracket': '['},
              {'name': 'class_name', 'required': True, 'bracket': '{'})
          try:
              parsed = next(command.parse(self._tex))
          except StopIteration:
              self._logger.warning('lsstdoc has no documentclass')
              self._document_options = []
  
          try:
              content = parsed['options']
              self._document_options = [opt.strip()
                                        for opt in content.split(',')]
          except KeyError:
              self._logger.warning('lsstdoc has no documentclass options')
              self._document_options = []
docs: Parse documentclass options.
  
          Sets the the ``_document_options`` attribute.