Is There a Problem With My C++ 17 Parallel Algorithm?

The problem that I'm trying to get Bryce to see is that we're using a scan operation and I'm expecting the output to be one, two, three. And so what is the problem with my current code? And if you want to hint, Bryce, if you look at the three commented outlines underneath, that was my first attempt to just hack it so that it would work. What is rather reverse, is it? Yeah. Oh, yeah. So basically I just want a scan that operates the same way that. Haskell developers that are listening will know.