src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts/NotebookTextModel/_mergeCellEdits
class NotebookTextModel:	private _mergeCellEdits(rawEdits: TransformedEdit[]): TransformedEdit[] {
		const mergedEdits: TransformedEdit[] = [];

		rawEdits.forEach(edit => {
			if (mergedEdits.length) {
				const last = mergedEdits[mergedEdits.length - 1];

				if (last.edit.editType === CellEditType.Output
					&& last.edit.append
					&& edit.edit.editType === CellEditType.Output
					&& edit.edit.append
					&& last.cellIndex === edit.cellIndex
				) {
					last.edit.outputs = [...last.edit.outputs, ...edit.edit.outputs];
				} else if (last.edit.editType === CellEditType.Output
					&& !last.edit.append // last cell is not append
					&& last.edit.outputs.length === 0 // last cell is clear outputs
					&& edit.edit.editType === CellEditType.Output
					&& edit.edit.append
					&& last.cellIndex === edit.cellIndex
				) {
					last.edit.append = false;
					last.edit.outputs = edit.edit.outputs;
				} else {
					mergedEdits.push(edit);
				}
			} else {
				mergedEdits.push(edit);
			}
		});

		return mergedEdits;
	}