How I wrote “Epoch From Calendar” tool

You may be one of people, that like me, have to deal with epoch. For those fortunate to not know what it is, it is a format of representation of time in seconds. People just chose a date in the past, and count seconds to every other date. For example 1643995442 marks 1643995442 seconds since the “start date”.

It is a fancy way of representing date, that has a great advantage: it can be saved in a database column of integer type. However, for people, it is not so great, because it’s hard to imagine birthday based on epoch.