Robocopy – How was it made? Like its code/coding language? [closed]

I wanna know like the code behind the code. Like the nit and grit of Robocopy. I don’t really know how to word it. I find it to be a very interesting program/command and I’m just curious.

I’m not looking for it’s history or it’s use cases. I’m looking for its coding (or at least its coding language).