src/vs/workbench/contrib/notebook/browser/contrib/fold/folding.ts/FoldingController/setFoldingStateUp
class FoldingController:	setFoldingStateUp(index: number, state: CellFoldingState, levels: number) {
		if (!this._foldingModel) {
			return;
		}

		let regions = this._foldingModel.getAllRegionsAtLine(index + 1, (region, level) => region.isCollapsed !== (state === CellFoldingState.Collapsed) && level <= levels);
		regions.forEach(r => this._foldingModel!.setCollapsed(r.regionIndex, state === CellFoldingState.Collapsed));
		this._updateEditorFoldingRanges();
	}