src/vs/workbench/api/common/extHostNotebookDocument.ts/RawContentChangeEvent/asApiEvent
class RawContentChangeEvent:	asApiEvent(): vscode.NotebookDocumentContentChange {
		return {
			range: new NotebookRange(this.start, this.start + this.deletedCount),
			addedCells: this.items.map(cell => cell.apiCell),
			removedCells: this.deletedItems,
		};
	}