protected function _merge($metrics = [], $line = false)
    {
        $defaults = [
            'loc'      => [],
            'nlloc'    => [],
            'lloc'     => [],
            'cloc'     => [],
            'files'    => [],
            'methods'  => 0,
            'cmethods' => 0
        ];
        $metrics += $defaults;

        foreach (['loc', 'nlloc', 'lloc', 'cloc', 'coverage', 'files', 'methods', 'cmethods'] as $name) {
            $metrics[$name] += $this->_metrics[$name];
        }
        if (!$line) {
            unset($metrics['line']);
        }
        $this->data($metrics);
    }