src/vs/workbench/contrib/notebook/browser/viewModel/notebookViewModel.ts/NotebookViewModel/validateRange
class NotebookViewModel:	validateRange(cellRange: ICellRange | null | undefined): ICellRange | null {
		if (!cellRange) {
			return null;
		}

		const start = clamp(cellRange.start, 0, this.length);
		const end = clamp(cellRange.end, 0, this.length);

		if (start === end) {
			return null;
		}

		if (start < end) {
			return { start, end };
		} else {
			return { start: end, end: start };
		}
	}