docs: def highlighted_fulltext(self):
          """Highlight the found terms in the fulltext."""
          terms = self.fields.get('fulltext', [])
          if not terms:
              return None
          arguments = {'id': self['id'],
                       'query': ' & '.join(terms),
                       }
          with db_connect() as db_connection:
              with db_connection.cursor() as cursor:
                  cursor.execute(_read_sql_file('highlighted-fulltext'),
                                 arguments)
                  hl_fulltext = cursor.fetchone()[0]
          return hl_fulltext