public function passArray(array $expression)
    {
        foreach ($expression['left'] as $item) {
            $usePass = self::DETECT_ARRAY_USE == ($this->detectionFlags & self::DETECT_ARRAY_USE);
            if ($usePass && 'variable' == $item['value']['type']) {
                $this->increaseMutations($item['value']['value']);
            } else {
                $this->passExpression($item['value']);
            }
        }
    }