code: def compare_config(self):
          
          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()
docs: Implementation of NAPALM method compare_config.