src/vs/workbench/api/common/extHostTypes.ts/NotebookRange/constructor
class NotebookRange:	constructor(start: number, end: number) {
		if (start < 0) {
			throw illegalArgument('start must be positive');
		}
		if (end < 0) {
			throw illegalArgument('end must be positive');
		}
		if (start <= end) {
			this._start = start;
			this._end = end;
		} else {
			this._start = end;
			this._end = start;
		}
	}