code: func (client *Client) BulkLinkRichMenu(richMenuID string, userIDs ...string) *BulkLinkRichMenuCall {
  	return &BulkLinkRichMenuCall{
  		c:          client,
  		userIDs:    userIDs,
  		richMenuID: richMenuID,
  	}
  }
docs: // BulkLinkRichMenu method