public function stop($key)
    {
        $benchmark = $this->get($key);

        $benchmark['stop_time'] = microtime(true);
        $benchmark['avg_time']  = $benchmark['stop_time'] - $benchmark['start_time'];
        $benchmark['stop_memory']   = memory_get_usage(true);
        $benchmark['avg_memory']    = ( ($benchmark['stop_memory'] - $benchmark['start_memory']) / 1024 ) / 1024;
        $benchmark['peak_memory']   = memory_get_peak_usage(true) / 1024 / 1024;
        $benchmark['running']       = false;

        $this->benchmarks[$key] = $benchmark;
    }