src/vs/editor/contrib/folding/folding.ts/UnfoldAction/invoke
class UnfoldAction:	invoke(_foldingController: FoldingController, foldingModel: FoldingModel, editor: ICodeEditor, args: FoldingArguments): void {
		let levels = args && args.levels || 1;
		let lineNumbers = this.getLineNumbers(args, editor);
		if (args && args.direction === 'up') {
			setCollapseStateLevelsUp(foldingModel, false, levels, lineNumbers);
		} else {
			setCollapseStateLevelsDown(foldingModel, false, levels, lineNumbers);
		}
	}