D: How do I pipe (|) through three programs using std.process?

[BoQsc]

Latest iteration on this thread.

Limitations:
* pipes through two programs.
* very verbose, hard to use.

```
import std;
import std.process;

version (Windows) { enum Find = "find"; }
version (Posix) { enum Find = "grep"; }

void pipeTo(Pipe p, string nextprogram){
	spawnShell(nextprogram, p.readEnd, stdout);
  }

auto program(string name){
     Pipe p = std.process.pipe;
	spawnShell(name, stdin, p.writeEnd);
     return p;
}

void main()
{
     program("echo HelloWorld").pipeTo(nextprogram: Find ~ ` 
"HelloWorld"`);
}
```