Xhgui_Profile::_sumKeys PHP Method

    protected function _sumKeys($a, $b)
    {
        foreach ($this->_keys as $key) {
            if (!isset($a[$key])) {
                $a[$key] = 0;
            }
            $a[$key] += isset($b[$key]) ? $b[$key] : 0;
        }
        return $a;
    }