src/vs/workbench/contrib/notebook/common/services/notebookSimpleWorker.ts/NotebookEditorSimpleWorker/acceptNewModel
class NotebookEditorSimpleWorker:	public acceptNewModel(uri: string, data: NotebookData): void {
		this._models[uri] = new MirrorNotebookDocument(URI.parse(uri), data.cells.map(dto => new MirrorCell(
			(dto as unknown as IMainCellDto).handle,
			dto.source,
			dto.language,
			dto.cellKind,
			dto.outputs,
			dto.metadata
		)), data.metadata);
	}