def compare_config(self):
        """Implementation of NAPALM method compare_config."""
        if self.config_session is None:
            return ''
        else:
            commands = ['show session-config named %s diffs' % self.config_session]
            result = self.device.run_commands(commands, encoding='text')[0]['output']

            result = '\n'.join(result.splitlines()[2:])

            return result.strip()