How to properly Thread.sleep?

[Israel via Digitalmars-d-learn]

Ive tried using google but no matter what code i find it either 
doesnt work, compiler gives me errors or maybe the code is 
deprecated.

What is the proper way of adding sleep time to a program?
Ive tried..

import std.stdio;
import core.thread;

void main()
{
      writeln("Sleep..");
      sleep(200);
      writeln("done");
}

but all i get is a compiler error unidentified identifier sleep.

The documentation examples dont make sense. Why would it work 
this way?

Thread.sleep( dur!("msecs")( 50 ) );  // sleep for 50 milliseconds
Thread.sleep( dur!("seconds")( 5 ) ); // sleep for 5 seconds