src/vs/editor/contrib/suggest/suggestAlternatives.ts/SuggestAlternatives/_moveIndex
class SuggestAlternatives:	private static _moveIndex(fwd: boolean, model: CompletionModel, index: number): number {
		let newIndex = index;
		while (true) {
			newIndex = (newIndex + model.items.length + (fwd ? +1 : -1)) % model.items.length;
			if (newIndex === index) {
				break;
			}
			if (!model.items[newIndex].completion.additionalTextEdits) {
				break;
			}
		}
		return newIndex;
	}