src/vs/editor/contrib/folding/browser/foldingRanges.ts/BitField/set
class BitField:	public set(index: number, newState: boolean) {
		const arrayIndex = (index / 32) | 0;
		const bit = index % 32;
		const value = this._states[arrayIndex];
		if (newState) {
			this._states[arrayIndex] = value | (1 << bit);
		} else {
			this._states[arrayIndex] = value & ~(1 << bit);
		}
	}