public function passLetStatement(array $statement)
    {
        foreach ($statement['assignments'] as $assignment) {
            if (isset($assignment['expr'])) {
                $this->passExpression($assignment['expr']);
            }
            $this->increaseMutations($assignment['variable']);
            if (self::DETECT_VALUE_IN_ASSIGNMENT == ($this->detectionFlags & self::DETECT_VALUE_IN_ASSIGNMENT)) {
                if (isset($assignment['expr'])) {
                    if ('variable' == $assignment['expr']['type']) {
                        $this->increaseMutations($assignment['expr']['value']);
                        break;
                    }
                }
            }
        }
    }