Implement Wda custom server?

I have been reading the doc section How To Set Up And Customize WebDriverAgent Server and I would like to implement this for myself. The code references UnixProcessHelpers. Does anyone know where to get his library? The only hint I have found on the web are a few other people implementing this same code, but I can’t find the library.

For example this gist contains the line
import static utils.UnixProcessHelpers.isProcessRunning;
but with no clue where to get the library.

Does anyone have experience implementing their own WDA custom server?

trying also to find UnixProcessHelpers and Timedelta (okay, easy to rewrite this one) without any success, maybe now have to use command line tools and decide from their results. Please notify if someone has this lib. Thanks.