public function addLoader($extensions, $loaderClass)
	{
		foreach ((array) $extensions as $extension) {
			$this->extensions[] = $extension;
			if (is_string($loaderClass)) {
				$this->loaderClasses[$extension] = $loaderClass;
			} elseif ($loaderClass instanceof LoaderInterface) {
				$this->loaders[$extension] = $loaderClass;
			}
		}
	}