src/vs/editor/common/model/bracketPairsTextModelPart/bracketPairsTree/smallImmutableSet.ts/SmallImmutableSet/create
class SmallImmutableSet:	private static create<T>(items: number, additionalItems: readonly number[]): SmallImmutableSet<T> {
		if (items <= 128 && additionalItems.length === 0) {
			// We create a cache of 128=2^7 elements to cover all sets with up to 7 (dense) elements.
			let cached = SmallImmutableSet.cache[items];
			if (!cached) {
				cached = new SmallImmutableSet(items, additionalItems);
				SmallImmutableSet.cache[items] = cached;
			}
			return cached;
		}

		return new SmallImmutableSet(items, additionalItems);
	}