src/vs/workbench/contrib/notebook/browser/view/cellPart.ts/CellPartsCollection/concatOverlayPart
class CellPartsCollection:	concatOverlayPart(other: readonly CellOverlayPart[]): CellPartsCollection {
		return new CellPartsCollection(this.contentParts, this.overlayParts.concat(other));
	}