code: public function revokeAll($userId)
      {
          if (isset($this->assignments[$userId]) && is_array($this->assignments[$userId])) {
              foreach ($this->assignments[$userId] as $itemName => $value) {
                  unset($this->assignments[$userId][$itemName]);
              }
              $this->saveAssignments();
              return true;
          }
  
          return false;
      }
docs: {@inheritdoc}