public function raiseCounter($key, $counterName)
    {

        // raise/initialize the value
        if (isset($this->attributes[$key][$counterName])) {
            $this->attributes[$key][$counterName]++;
        } else {
            $this->attributes[$key][$counterName] = 1;
        }

        // return the new value
        return $this->attributes[$key][$counterName];
    }