src/vs/editor/common/model/bracketPairsTextModelPart/bracketPairsTree/smallImmutableSet.ts/SmallImmutableSet/has
class SmallImmutableSet:	public has(value: T, keyProvider: IDenseKeyProvider<T>): boolean {
		const key = keyProvider.getKey(value);
		let idx = key >> 5; // divided by 32
		if (idx === 0) {
			// fast path
			return (this.items & (1 << key)) !== 0;
		}
		idx--;

		return ((this.additionalItems[idx] || 0) & (1 << (key & 31))) !== 0;
	}