code: protected function getRememberKey()
      {
          $backtrace = debug_backtrace(4)[2];
          $args = implode('_', $backtrace['args']);
          $key = str_replace('\\', '_', get_class($this).'_'.$backtrace['function'].'_'.$args);
  
          return $key;
      }
docs: get the cache key.
  
  @return string