Best way to add slash to tail of the path

[Suliman via Digitalmars-d-learn]

>take a second look then. ;-) you'll find `buildPath()` here too.
Not better:

	string foo = "D:/code/txtDownloader";

	writeln(foo);
	foo = foo.buildPath;
	foo ~= "config.txt";
	writeln(foo);


Running .\txtdownloader.exe
D:/code/txtDownloader
D:/code/txtDownloaderconfig.txt <-- need: 
D:/code/txtDownloader/config.txt