src/vs/base/browser/ui/tree/compressedObjectTreeModel.ts/CompressibleObjectTreeModel/getLastElementAncestor
class CompressibleObjectTreeModel:	getLastElementAncestor(location?: T | null | undefined): T | null | undefined {
		const result = this.model.getLastElementAncestor(location);

		if (result === null || typeof result === 'undefined') {
			return result;
		}

		return this.elementMapper(result.elements);
	}