Simplifying process piping

[Jesse Phillips]

As noted in this announcement, I started writing some basic 
tutorials for D.

https://forum.dlang.org/post/efpyegvrezybdrmugipd@forum.dlang.org

At a post a week, I've got 10 weeks of backlog posts. One of 
these is a post on input output piping.

https://github.com/JesseKPhillips/std.process-example/

I'm wondering if there are any thoughts for simplification. I 
don't mean simplify to perform the same end result, but is the 
threading and data copies as simple as they could be? Did I 
misrepresent anything?