public function invert($index = 0) {
		$pcs = $this->bits;
		$pcs = \ianring\BitmaskUtils::reflectBitmask($pcs);
		$pcs = \ianring\BitmaskUtils::rotateBitmask($pcs, -1, 1);
		$pcs = \ianring\BitmaskUtils::rotateBitmask($pcs, 0, $index);
		$this->bits = $pcs;
	}