code: private void delete(File file) {
  
  		// Assertions.
  		if (file == null) {
  			String msg = "Argument 'file' cannot be null.";
  			throw new IllegalArgumentException(msg);
  		}
  
  		if (file.isDirectory()) {
  			for (File f : file.listFiles()) {
  				delete(f);
  			}
  		}
  
  		file.delete();
  
  	}
docs: /*
  Private Stuff.