https://naiwaen.debuggingsoft.com/2020/11/c-gethashcode-%e0%b9%84%e0%b8%a1%e0%b9%88%e0%b9%80%e0%b8%97%e0%b9%88%e0%b8%b2%e0%b8%81%e0%b8%b1%e0%b8%9a-equals-%e0%b8%99%e0%b8%b0/