https://blog.faceutil.com/2017/04/05/%ed%94%8c%eb%9e%98%ec%8b%9c-%ea%b0%95%ec%a2%8c-action-script-3-0-%eb%b2%84%ed%8a%bc%eb%a7%8c%eb%93%a4%ea%b8%b0-%ce%b3/