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

[Suliman via Digitalmars-d-learn]

        foreach(f; files))
        {
                if (canFind(to!string(f), " "))
                {
                        writeln("whitespace found:");
                        writeln(f);
    			Thread.sleep( dur!("msecs")( 50 ) );  // sleep for 50 
milliseconds
                }
                else
                        continue;
        }
Error: module app struct std.regex.Thread(DataIndex) is private
Error: no property 'sleep' for type 'void'

What's wrong? Why sleeping do not work?