docs: def highlighted_abstract(self):
          """Highlight the found terms in the abstract text."""
          abstract_terms = self.fields.get('abstract', [])
          if abstract_terms:
              sql = _read_sql_file('highlighted-abstract')
          else:
              sql = _read_sql_file('get-abstract')
          arguments = {'id': self['id'],
                       'query': ' & '.join(abstract_terms),
                       }
          with db_connect() as db_connection:
              with db_connection.cursor() as cursor:
                  cursor.execute(sql, arguments)
                  hl_abstract = cursor.fetchone()
          if hl_abstract:
              return hl_abstract[0]