src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts/NotebookTextModel/_commonPrefix
class NotebookTextModel:	private static _commonPrefix(a: readonly NotebookCellTextModel[], aLen: number, aDelta: number, b: ICellDto2[], bLen: number, bDelta: number): number {
		const maxResult = Math.min(aLen, bLen);
		let result = 0;
		for (let i = 0; i < maxResult && a[aDelta + i].fastEqual(b[bDelta + i]); i++) {
			result++;
		}

		return result;
	}