https://naiwaen.debuggingsoft.com/2020/10/%e0%b8%babpmn-%e0%b8%81%e0%b8%b1%e0%b8%9a-uml-%e0%b9%81%e0%b8%95%e0%b8%81%e0%b8%95%e0%b9%88%e0%b8%b2%e0%b8%87%e0%b8%81%e0%b8%b1%e0%b8%99%e0%b8%ad%e0%b8%a2%e0%b9%88%e0%b8%b2%e0%b8%87%e0%b9%84%e0%b8%a3/